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Information on EC 2.7.1.180 - FAD:protein FMN transferase
for references in articles please use BRENDA:EC2.7.1.180
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EC Tree 2 Transferases
2.7 Transferring phosphorus-containing groups
2.7.1 Phosphotransferases with an alcohol group as acceptor
2.7.1.180 FAD:protein FMN transferase
IUBMB Comments
The enzyme catalyses the transfer of the FMN portion of FAD and its covalent binding to the hydroxyl group of an L-threonine residue in a target flavin-binding protein such as the B and C subunits of EC 7.2.1.1, NADH:ubiquinone reductase (Na+-transporting). Requires Mg2+.
The expected taxonomic range for this enzyme is: Bacteria, Eukaryota, Archaea
- 2.7.1.180
-
flavinylation
- vibrio
- flavoproteins
-
na+-translocating
-
nadh:quinone
-
phosphoester
- mononucleotide
- fumarate
- cholerae
-
klebsiella
- pneumoniae
- na+-nqr
- harveyi
-
fluorogenic
- proteobacteria
-
prosthetic
- pallidum
-
fmn-binding
-
redox-active
-
metal-dependent
-
spirochete
-
syphilis
- isoalloxazine
- pyrophosphatase
Reaction Schemes
show+
=
[protein]-FMN-L-threonine
+
Synonyms
flavin transferase, flavin-trafficking protein, apbe1, apbe2, fmn transferase, more
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SYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
apbE
ApbE1
ApbE2
FAD:threonine flavin transferases
flavin transferase
FMN transferase
Ftp
Mg2+-dependent FAD:protein FMN transferase
Mg2+-dependent FMN transferase
protein-dependent FMN transferase
additional information
apbE
-
-
-
-
flavin transferase
-
-
-
-
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
FAD + [protein]-L-threonine = [protein]-FMN-L-threonine + AMP
-
-
-
-
FAD + [protein]-L-threonine = [protein]-FMN-L-threonine + AMP
in the random Bi Bi kinetic mechanism of ApbE reaction, His257 acts as a general base that deprotonates the acceptor residue, which subsequently performs a nucleophilic attack on FAD for flavin transfer
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SYSTEMATIC NAME
IUBMB Comments
FAD:protein riboflavin-5'-phosphate transferase
The enzyme catalyses the transfer of the FMN portion of FAD and its covalent binding to the hydroxyl group of an L-threonine residue in a target flavin-binding protein such as the B and C subunits of EC 7.2.1.1, NADH:ubiquinone reductase (Na+-transporting). Requires Mg2+.
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SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
LITERATURE
COMMENTARY
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
FAD + L-threonyl-[Shewanella oneidensis NqrC protein]
AMP + FMN-L-threonyl-[Shewanella oneidensis NqrC protein] + H+
Substrates: a high-resolution structure of the Ftp-mediated flavinylated protein of Shewanella oneidensis NqrC identifies an essential lysine in phosphoester-threonyl-FMN bond formation in the posttranslationally modified flavoproteins
Products: -
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?
FAD + [Klebsiella pneumoniae cytoplasmic fumarate reductase]-L-threonine
[Klebsiella pneumoniae cytoplasmic fumarate reductase]-FMN-L-threonine + AMP
Substrates: -
Products: -
Products: -
?
FAD + [NqrC subunit of Vibrio harveyi Na+-translocating NADH:quinone oxidoreductase]-L-threonine
[NqrC subunit of Vibrio harveyi Na+-translocating NADH:quinone oxidoreductase]-FMN-L-threonine + AMP
Substrates: -
Products: -
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?
FAD + [periplasmic redox-carrying protein RnfG_Ec]-L-threonine
[periplasmic redox-carrying protein RnfG_Ec]-FMN-L-threonine + AMP
Substrates: flavinylating via the metal-dependent covalent attachment of FMN
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?
FAD + [protein NqrC]-L-threonine
[protein NqrC]-FMN-L-threonine + AMP
Substrates: -
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?
FAD + [protein]-L-serine
[protein]-FMN-L-serine + AMP
Substrates: 45-90% activity compared to threonine as acceptor with wild-type and mutant enzymes
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FAD + [Shewanella oneidensis protein NqrC]-L-threonine
[Shewanella oneidensis protein NqrC]-FMN-L-threonine + AMP
Substrates: a subunit (NqrC) of a cytoplasmic membrane redox system (Nqr), detection of an essential lysine residue in phosphoester-threonyl-FMN bond formation in the posttranslationally modified flavoprotein
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FAD + [Vibrio cholerae protein NqrC]-L-threonine
[Vibrio cholerae protein NqrC]-FMN-L-threonine + AMP
FAD + L-threonyl-[NqrC protein]
AMP + FMN-L-threonyl-[NqrC protein] + H+
Substrates: -
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FAD + L-threonyl-[NqrC protein]
AMP + FMN-L-threonyl-[NqrC protein] + H+
Substrates: -
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?
FAD + L-threonyl-[NqrC protein]
AMP + FMN-L-threonyl-[NqrC protein] + H+
Substrates: -
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?
FAD + L-threonyl-[NqrC protein]
AMP + FMN-L-threonyl-[NqrC protein] + H+
Substrates: -
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?
FAD + L-threonyl-[NqrC protein]
AMP + FMN-L-threonyl-[NqrC protein] + H+
Substrates: -
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?
FAD + L-threonyl-[NqrC protein]
AMP + FMN-L-threonyl-[NqrC protein] + H+
Substrates: -
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?
FAD + L-threonyl-[NqrC protein]
AMP + FMN-L-threonyl-[NqrC protein] + H+
Substrates: -
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?
FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: -
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?
FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: -
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?
FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: RnfG_Ec subunit of the Rnf_Ec-redox system of Escherichia coli
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?
FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: -
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FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: RnfG_Ec subunit of the Rnf_Ec-redox system of Escherichia coli
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?
FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: -
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FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: -
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?
FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: -
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?
FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: -
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FAD + L-threonyl-[RnfG protein]
AMP + FMN-L-threonyl-[RnfG protein] + H+
Substrates: RnfG subunit of the Rnf redox system
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?
FAD + L-threonyl-[RnfG protein]
AMP + FMN-L-threonyl-[RnfG protein] + H+
Substrates: RnfG subunit of the Rnf redox system
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?
FAD + L-threonyl-[RnfG protein]
AMP + FMN-L-threonyl-[RnfG protein] + H+
Substrates: RnfG subunit of the Rnf redox system
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?
FAD + L-threonyl-[RnfG protein]
AMP + FMN-L-threonyl-[RnfG protein] + H+
Substrates: RnfG subunit of the Rnf redox system
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?
FAD + L-threonyl-[RnfG protein]
AMP + FMN-L-threonyl-[RnfG protein] + H+
Substrates: RnfG subunit of the Rnf redox system
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?
FAD + L-threonyl-[RnfG protein]
AMP + FMN-L-threonyl-[RnfG protein] + H+
Substrates: RnfG subunit of the Rnf redox system
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?
FAD + L-threonyl-[RnfG protein]
AMP + FMN-L-threonyl-[RnfG protein] + H+
Substrates: RnfG subunit of the Rnf redox system
Products: -
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
Substrates: -
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
Substrates: -
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
Substrates: -
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
Substrates: preferred substrate
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
Substrates: -
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
Substrates: -
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
Substrates: -
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
-
Substrates: -
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
-
Substrates: -
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?
FAD + [Vibrio cholerae protein NqrC]-L-threonine
[Vibrio cholerae protein NqrC]-FMN-L-threonine + AMP
Substrates: -
Products: -
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?
FAD + [Vibrio cholerae protein NqrC]-L-threonine
[Vibrio cholerae protein NqrC]-FMN-L-threonine + AMP
Substrates: conserved Lys207 in NqrC can account for the pH dependency
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?
additional information
?
-
Substrates: the flavin-trafficking protein (Ftp) catalyzes the transfer of the FMN moiety of FAD and its covalent binding to the hydroxyl group of a threonine residue in a target flavoprotein (EC 2.7.1.180). The enzyme is capable of flavinylating periplasmic redox-carrying proteins (e.g., RnfG_Ec) via the metal-dependent covalent attachment of FMN. A single amino acid substitution Y60N converts it from an FAD-binding protein to a Mg2+-dependent FAD diphosphatase (Ftp_Tp-like) (EC 3.6.1.18). The engineered protein variant (Ftp_EcY60A) shows Mg2+-dependent FAD diphosphatase activity, but also retains its Mg2+-dependent FMN transferase (EC 2.7.1.180) activity on the protein substrate, indicating that the protein variant enzyme has dual activity. The Ftp_EcY60A protein variant binds FAD, yet rapidly hydrolyzes it and the product FMN dissociates. Substrate binding structures, detailed overview
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additional information
?
-
-
Substrates: the flavin-trafficking protein (Ftp) catalyzes the transfer of the FMN moiety of FAD and its covalent binding to the hydroxyl group of a threonine residue in a target flavoprotein (EC 2.7.1.180). The enzyme is capable of flavinylating periplasmic redox-carrying proteins (e.g., RnfG_Ec) via the metal-dependent covalent attachment of FMN. A single amino acid substitution Y60N converts it from an FAD-binding protein to a Mg2+-dependent FAD diphosphatase (Ftp_Tp-like) (EC 3.6.1.18). The engineered protein variant (Ftp_EcY60A) shows Mg2+-dependent FAD diphosphatase activity, but also retains its Mg2+-dependent FMN transferase (EC 2.7.1.180) activity on the protein substrate, indicating that the protein variant enzyme has dual activity. The Ftp_EcY60A protein variant binds FAD, yet rapidly hydrolyzes it and the product FMN dissociates. Substrate binding structures, detailed overview
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?
additional information
?
-
Substrates: the Escherichia coli enzyme shows no Mg2+-dependent FAD pyrophosphatase (EC 3.6.1.18) activity
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?
additional information
?
-
-
Substrates: the Escherichia coli enzyme shows no Mg2+-dependent FAD pyrophosphatase (EC 3.6.1.18) activity
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?
additional information
?
-
Substrates: Klebsiella pneumoniae ApbE can modify both threonine and serine residues in the position 447 of FRD resulting in their similar activities, although serine is modified less readily
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?
additional information
?
-
-
Substrates: Klebsiella pneumoniae ApbE can modify both threonine and serine residues in the position 447 of FRD resulting in their similar activities, although serine is modified less readily
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?
additional information
?
-
Substrates: the flavin-trafficking protein (Ftp) catalyzes the transfer of the FMN moiety of FAD and its covalent binding to the hydroxyl group of a threonine residue in a target flavoprotein (EC 2.7.1.180). The enzyme is capable of flavinylating periplasmic redox-carrying proteins (e.g., RnfG_Ec) via the metal-dependent covalent attachment of FMN. It also displays FAD diphosphatase activity in vitro, hydrolyzing FAD into FMN and AMP (EC 3.6.1.18). Substrate binding structures, detailed overview
Products: -
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?
additional information
?
-
-
Substrates: the flavin-trafficking protein (Ftp) catalyzes the transfer of the FMN moiety of FAD and its covalent binding to the hydroxyl group of a threonine residue in a target flavoprotein (EC 2.7.1.180). The enzyme is capable of flavinylating periplasmic redox-carrying proteins (e.g., RnfG_Ec) via the metal-dependent covalent attachment of FMN. It also displays FAD diphosphatase activity in vitro, hydrolyzing FAD into FMN and AMP (EC 3.6.1.18). Substrate binding structures, detailed overview
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?
additional information
?
-
Substrates: the His257 residue plays important roles in catalysis and in enzyme-substrate complex formation and in substrate deprotonation, proposed mechanism of flavin transfer
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?
additional information
?
-
-
Substrates: the His257 residue plays important roles in catalysis and in enzyme-substrate complex formation and in substrate deprotonation, proposed mechanism of flavin transfer
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?
additional information
?
-
Substrates: substrate specificity, overview. FAD cannot be substituted by FMN
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?
additional information
?
-
Substrates: enzyme ApbE covalently attaches flavin residues to threonine residues of Na+-translocating NADH:quinone oxidoreductase maturation, Na+-NQR
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?
additional information
?
-
-
Substrates: enzyme ApbE covalently attaches flavin residues to threonine residues of Na+-translocating NADH:quinone oxidoreductase maturation, Na+-NQR
Products: -
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?
additional information
?
-
Substrates: enzyme ApbE covalently attaches flavin residues to threonine residues of Na+-translocating NADH:quinone oxidoreductase maturation, Na+-NQR
Products: -
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?
additional information
?
-
-
Substrates: no activity with FMN
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?
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NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
LITERATURE
COMMENTARY
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
FAD + [Klebsiella pneumoniae cytoplasmic fumarate reductase]-L-threonine
[Klebsiella pneumoniae cytoplasmic fumarate reductase]-FMN-L-threonine + AMP
Substrates: -
Products: -
Products: -
?
FAD + [Vibrio cholerae protein NqrC]-L-threonine
[Vibrio cholerae protein NqrC]-FMN-L-threonine + AMP
Substrates: -
Products: -
Products: -
?
FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: -
Products: -
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?
FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: -
Products: -
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?
FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: -
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?
FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: -
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?
FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: -
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?
FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: -
Products: -
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?
FAD + L-threonyl-[protein]
AMP + FMN-L-threonyl-[protein] + H+
Substrates: -
Products: -
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
Substrates: -
Products: -
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
Substrates: -
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
Substrates: -
Products: -
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
Substrates: -
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
Substrates: -
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
Substrates: -
Products: -
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?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
-
Substrates: -
Products: -
Products: -
?
FAD + [protein]-L-threonine
[protein]-FMN-L-threonine + AMP
-
Substrates: -
Products: -
Products: -
?
additional information
?
-
Substrates: enzyme ApbE covalently attaches flavin residues to threonine residues of Na+-translocating NADH:quinone oxidoreductase maturation, Na+-NQR
Products: -
Products: -
?
additional information
?
-
-
Substrates: enzyme ApbE covalently attaches flavin residues to threonine residues of Na+-translocating NADH:quinone oxidoreductase maturation, Na+-NQR
Products: -
Products: -
?
additional information
?
-
Substrates: enzyme ApbE covalently attaches flavin residues to threonine residues of Na+-translocating NADH:quinone oxidoreductase maturation, Na+-NQR
Products: -
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Ca2+
presence of a Ca2+ ion in metal site 1 in the apo form of mutant Ftp_EcY60N, the Ca2+ ion serves a role in properly positioning substrate and protein residues
Mg2+
additional information
Mg2+
dependent on, metal-dependent enzyme, bimetal center in the crystal structure of Escherichia coli Ftp
Mg2+
required, dependent on, Mg2+ ion is directly involved in catalysis. A single metal ion is bound in the wild-type enzyme and mutant Ftp_EcE169K structures. The inhibited mutant Ftp_EcY60N contains a bimetal Mg2+ center
Mg2+
required for catalysis, Mg2+ does not play a major role in stabilizing the interaction of the protein with FAD, Mg2+ in the preferred divalent cation
additional information
identification of a bimetal center in the crystal structure of Escherichia coli Ftp (Ftp_Ec)
additional information
-
identification of a bimetal center in the crystal structure of Escherichia coli Ftp (Ftp_Ec)
additional information
divalent cations are essential for ApbE activity, and their removal by EDTA abolishes the activity. ApbE is also able to use other divalent cations, such as Mn2+ and Co2+, obtaining a similar activity compared to Mg2+. The coordination sphere of ApbE enzymes largely determines the specificity of the enzyme for the divalent cation
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INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
ADP
the Ftp_EcY60N enzyme mutant displays FAD diphosphatase activity that is inhibited by ADP
ATP
1 mM of ATP has no effect on the activity, but a higher concentration (10 mM), produces a slight inhibition
FMN
1 mM of FMN has no effect on the activity, but a higher concentration (10 mM), produces a slight inhibition
n-dodecyl-beta-D-maltopyranoside
0.05% n-dodecyl-beta-D-maltopyranoside causes 20% inhibition of the enzyme
AMP
mixed inhibitor, AMP behaves as a mixed inhibitor versus substrate NqrC, but is also bound uncompetitively to the modified form (E-NqrC-FMN), explaining the mixed behavior
AMP
1 mM of AMP has no effect on the activity, but a higher concentration (10 mM), produces a slight inhibition
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ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
ADP
ADP does not inhibit the transfer reaction, but significantly activates it by 6fold
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DISEASE
TITLE OF PUBLICATION
LINK TO PUBMED
Syphilis
Evidence for Posttranslational Protein Flavinylation in the Syphilis Spirochete Treponema pallidum: Structural and Biochemical Insights from the Catalytic Core of a Periplasmic Flavin-Trafficking Protein.
Syphilis
Molecular insights into the enzymatic diversity of flavin-trafficking protein (Ftp; formerly ApbE) in flavoprotein biogenesis in the bacterial periplasm.
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.1
[Vibrio cholerae protein NqrC]-L-threonine
above, pH 9.0, 22°C, recombinant wild-type enzyme
-
0.0001
FAD
pH 9.0, temperature not specified in the publication, wild-type enzyme
0.00019
FAD
pH 9.0, temperature not specified in the publication, mutant H257t
0.0002
FAD
pH 9.0, temperature not specified in the publication, mutant H257G
0.011
[protein NqrC]-L-threonine
pH 9.0, temperature not specified in the publication, wild-type enzyme
-
0.087
[protein NqrC]-L-threonine
pH 9.0, temperature not specified in the publication, mutant H257G
-
0.119
[protein NqrC]-L-threonine
pH 9.0, temperature not specified in the publication, mutant H257t
-
additional information
additional information
ApbE follows a random Bi Bi sequential kinetic mechanism, in which a ternary complex is formed, indicating that both substrates must be bound to the enzyme for the reaction to proceed, Michaelis-Menten steady-state kinetic analysis, kinetic mechanism
-
additional information
additional information
-
ApbE follows a random Bi Bi sequential kinetic mechanism, in which a ternary complex is formed, indicating that both substrates must be bound to the enzyme for the reaction to proceed, Michaelis-Menten steady-state kinetic analysis, kinetic mechanism
-
additional information
additional information
single-turnover kinetics
-
additional information
additional information
ApbE activity is highly sensitive to FAD, and is saturated at 0.001 mM
-
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TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.00026
FAD
pH 9.0, temperature not specified in the publication, mutant H257E
0.00095
FAD
pH 9.0, temperature not specified in the publication, mutant H257K
0.036
FAD
pH 9.0, temperature not specified in the publication, mutant H257t
0.045
FAD
pH 9.0, temperature not specified in the publication, mutant H257G
0.16
FAD
pH 9.0, temperature not specified in the publication, wild-type enzyme
0.00026
[protein NqrC]-L-threonine
pH 9.0, temperature not specified in the publication, mutant H257E
-
0.00095
[protein NqrC]-L-threonine
pH 9.0, temperature not specified in the publication, mutant H257K
-
0.036
[protein NqrC]-L-threonine
pH 9.0, temperature not specified in the publication, mutant H257t
-
0.045
[protein NqrC]-L-threonine
pH 9.0, temperature not specified in the publication, mutant H257G
-
0.16
[protein NqrC]-L-threonine
pH 9.0, temperature not specified in the publication, wild-type enzyme
-
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kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
189.5
FAD
pH 9.0, temperature not specified in the publication, mutant H257t
225
FAD
pH 9.0, temperature not specified in the publication, mutant H257G
1600
FAD
pH 9.0, temperature not specified in the publication, wild-type enzyme
0.303
[protein NqrC]-L-threonine
pH 9.0, temperature not specified in the publication, mutant H257t
-
0.52
[protein NqrC]-L-threonine
pH 9.0, temperature not specified in the publication, mutant H257G
-
14.55
[protein NqrC]-L-threonine
pH 9.0, temperature not specified in the publication, wild-type enzyme
-
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
7.5
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TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
37
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ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
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LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
Highest Expressing Human Cell Lines
Cell Line LinksPlease wait a moment until the data is sorted. This message will disappear when the data is sorted.
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
evolution
malfunction
physiological function
additional information
evolution
there likely are two classes of Ftps, one associated with FAD-binding and the other with FAD hydrolysis
evolution
there likely are two classes of Ftps, one associated with FAD-binding and the other with FAD hydrolysis
evolution
there likely are two classes of Ftps, one associated with FAD-binding and the other with FAD hydrolysis
evolution
FMN residue attached through a phosphoester bond is found in three types of protein architectures-prokaryotic FMN bind and NQR2 RnfD RnfE (PF03116) domains and an about 50-residue N-terminal extension of the ApbE domain in eukaryotic NADH:fumarate oxidoreductases. These three architectures are non-homologous, and their sequences have nothing in common, except for a short motif around the flavinylated residue. The motif common to all three flavinylated architectures can be depicted as Dxx(s/t)(g/s)At/s, where the last residue is the flavin acceptor. It is threonine in all characterized proteins of the first two groups, but it is sporadically replaced by serine in 3.5-5% of their putative homologues
evolution
ApbE is a member of a family of flavin transferases that incorporates flavin mononucleotide (FMN) to subunits of diverse respiratory complexes, which fulfill important homeostatic functions. Enzyme residue His257 is absolutely conserved in the family
evolution
-
there likely are two classes of Ftps, one associated with FAD-binding and the other with FAD hydrolysis
-
evolution
-
there likely are two classes of Ftps, one associated with FAD-binding and the other with FAD hydrolysis
-
evolution
-
there likely are two classes of Ftps, one associated with FAD-binding and the other with FAD hydrolysis
-
evolution
-
there likely are two classes of Ftps, one associated with FAD-binding and the other with FAD hydrolysis
-
malfunction
lesion in the ApbE2 gene in results in inactive cytoplasmic fumarate reductase, but Na+-translocating NADH:quinone oxidoreductase activity remains unchanged
malfunction
lesion in the ApbE1 gene in results in inactive Na+-translocating NADH:quinone oxidoreductase, but cytoplasmic fumarate reductase activity remains unchanged
malfunction
-
enzyme inactivation results in a complete loss of the quinone reductase activity of Na+-translocating NADH:quinone oxidoreductase
malfunction
a single amino acid substitution Y60N converts it from an FAD-binding protein to a Mg2+-dependent FAD diphosphatase (Ftp_Tp-like). The engineered protein variant (Ftp_EcY60A) shows Mg2+-dependent FAD diphosphatase activity, but also retains its Mg2+-dependent FMN transferase (EC 2.7.1.180) activity on the protein substrate, indicating that the protein variant enzyme has dual activity
malfunction
the replacement of the flavin acceptor threonine with alanine completely abolishes the modification reaction, whereas the replacements of conserved aspartate and serine had only minor effects. Effects of other substitutions, including replacing the acceptor threonine with serine, (a 10-55% decrease in the flavinylation degree). Replacements of conserved leucine and threonine residues in the binding pocket that accommodates FMN residue still allows appreciable flavinylation of the NqrC subunit of Vibrio harveyi Na+-translocating NADH:quinone oxidoreductase, despite a profound weakening of the isoalloxazine ring binding and an increase in its exposure to solvent
malfunction
a single amino acid substitution converts it from an FAD-binding protein to a Mg2+-dependent FAD diphosphatase (Ftp_Tp-like, EC 3.6.1.18)
malfunction
-
lesion in the ApbE2 gene in results in inactive cytoplasmic fumarate reductase, but Na+-translocating NADH:quinone oxidoreductase activity remains unchanged
-
malfunction
-
lesion in the ApbE1 gene in results in inactive Na+-translocating NADH:quinone oxidoreductase, but cytoplasmic fumarate reductase activity remains unchanged
-
malfunction
-
enzyme inactivation results in a complete loss of the quinone reductase activity of Na+-translocating NADH:quinone oxidoreductase
-
physiological function
-
ApbE is a modifying enzyme involved in the maturation of flavoproteins. ApbE is the only protein factor required for flavinylation of subunit NqrC in Na+-translocating NADH:quinone oxidoreductase
physiological function
Na+-translocating NADH:quinone oxidoreductase maturation involves covalent attachment of flavin mononucleotide (FMN) residues, catalyzed by flavin transferase encoded by the nqr-associated apbE gene
physiological function
the flavin-trafficking protein (Ftp) in the syphillis spirochete Treponema pallidum (Ftp_Tp) is a bacterial metal-dependent FAD diphosphatase that hydrolyzes FAD into AMP and FMN in the periplasm. Both types of Ftps are capable of flavinylating periplasmic redox-carrying proteins (e.g., RnfG_Ec) via the metal-dependent covalent attachment of FMN. Possible mechanism by which flavoproteins are generated, overview
physiological function
the flavin-trafficking protein (Ftp) catalyzes the transfer of the FMN moiety of FAD to a threonine residue in a target flavoprotein. Both types of Ftps are capable of flavinylating periplasmic redox-carrying proteins (e.g., RnfG_Ec) via the metal-dependent covalent attachment of FMN. Possible mechanism by which flavoproteins are generated, overview
physiological function
the flavin-trafficking protein (Ftp) catalyzes the transfer of the FMN moiety of FAD to a threonine residue in a target flavoprotein. Both types of Ftps are capable of flavinylating periplasmic redox-carrying proteins (e.g., RnfG_Ec) via the metal-dependent covalent attachment of FMN. Possible mechanism by which flavoproteins are generated, overview
physiological function
many flavoproteins belonging to three domain types contain an FMN residue linked through a phosphoester bond to a threonine or serine residue found in a conserved seven-residue motif. The flavinylation reaction is catalyzed by a specific enzyme, ApbE, which uses FAD as a substrate
physiological function
the enzyme flavinylate the redox subunit, NqrC, via its metal-dependent FMN transferase activity
physiological function
substrate specificity and regulatory mechanisms, overview. Residue H257 is the residue whose deprotonation controls the activity, it plays an important role in the catalytic mechanism of ApbE. Residue His257 is indeed essential for catalysis, but not for substrate binding
physiological function
-
the flavin-trafficking protein (Ftp) catalyzes the transfer of the FMN moiety of FAD to a threonine residue in a target flavoprotein. Both types of Ftps are capable of flavinylating periplasmic redox-carrying proteins (e.g., RnfG_Ec) via the metal-dependent covalent attachment of FMN. Possible mechanism by which flavoproteins are generated, overview
-
physiological function
-
ApbE is a modifying enzyme involved in the maturation of flavoproteins. ApbE is the only protein factor required for flavinylation of subunit NqrC in Na+-translocating NADH:quinone oxidoreductase
-
physiological function
-
the flavin-trafficking protein (Ftp) in the syphillis spirochete Treponema pallidum (Ftp_Tp) is a bacterial metal-dependent FAD diphosphatase that hydrolyzes FAD into AMP and FMN in the periplasm. Both types of Ftps are capable of flavinylating periplasmic redox-carrying proteins (e.g., RnfG_Ec) via the metal-dependent covalent attachment of FMN. Possible mechanism by which flavoproteins are generated, overview
-
physiological function
-
Na+-translocating NADH:quinone oxidoreductase maturation involves covalent attachment of flavin mononucleotide (FMN) residues, catalyzed by flavin transferase encoded by the nqr-associated apbE gene
-
physiological function
-
the flavin-trafficking protein (Ftp) catalyzes the transfer of the FMN moiety of FAD to a threonine residue in a target flavoprotein. Both types of Ftps are capable of flavinylating periplasmic redox-carrying proteins (e.g., RnfG_Ec) via the metal-dependent covalent attachment of FMN. Possible mechanism by which flavoproteins are generated, overview
-
physiological function
-
the flavin-trafficking protein (Ftp) catalyzes the transfer of the FMN moiety of FAD to a threonine residue in a target flavoprotein. Both types of Ftps are capable of flavinylating periplasmic redox-carrying proteins (e.g., RnfG_Ec) via the metal-dependent covalent attachment of FMN. Possible mechanism by which flavoproteins are generated, overview
-
additional information
the critical residue that contacts the isoalloxazine ring of FAD, is a tyrosine residue in the FAD-binding Ftps
additional information
-
the critical residue that contacts the isoalloxazine ring of FAD, is a tyrosine residue in the FAD-binding Ftps
additional information
the critical residue that contacts the isoalloxazine ring of FAD, is a tyrosine residue in the FAD-binding Ftps. FAD binding structure involving residue K207, overview
additional information
-
the critical residue that contacts the isoalloxazine ring of FAD, is a tyrosine residue in the FAD-binding Ftps. FAD binding structure involving residue K207, overview
additional information
the flavinylation motif of FRD, D-6A-5I-4S-3G-2A-1T0S+1 Q+2S+3 (zero position corresponds to Thr447 in the amino acid sequence), is mostly typical of FMN bind domain
additional information
-
the flavinylation motif of FRD, D-6A-5I-4S-3G-2A-1T0S+1 Q+2S+3 (zero position corresponds to Thr447 in the amino acid sequence), is mostly typical of FMN bind domain
additional information
residue His257 is located in the catalytic site and the mutational substitution does not produce major conformational changes
additional information
-
residue His257 is located in the catalytic site and the mutational substitution does not produce major conformational changes
additional information
-
the critical residue that contacts the isoalloxazine ring of FAD, is a tyrosine residue in the FAD-binding Ftps
-
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PDB
SCOP
CATH
UNIPROT
ORGANISM
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MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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SUBUNIT
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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CRYSTALLIZATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
purified Ftp_Ec mutant variant Y60N complexed with ADP, hanging drop vapor diffusion method, mixing of 0.004 ml of 20 mg/ml protein in Tris, pH 7.5, and 20 mM NaCl, with 0.04 ml of reservoir solution containing 0.2 M NH4NO3, and 20% w/v PEG 3350, and 0.001 ml of 50 mM MgCl2, and 0.001 ml of 50 mM ADP, 20°C, X-ray diffraction structure determination and analysis at 1.85 A resolution, molecular replacement and modelling
purified recombinant wild-type enzyme Ftp_Ec, mutant E169K, and mutant Y60N bound to ADP, hanging drop vapor diffusion method, mixing of 0.004 ml of 20 mg/ml protein in 20 mM Tris, pH 7.5, and 20 mM NaCl, with 0.004 ml of reservoir solution containing 0.2 M NH4NO3 and 20% w/v PEG 3350 for the wild-type, and 25% w/v PEG 1500, 0.1 M MIB (malonate, imidazole and boric acid), pH 5.0 for the mutant, 20°C, X-ray diffraction structure determination and analysis at 1.75-1.88 A resolution
purified recombinant His-tagged wild-type ApbE and H257G mutant, sitting drop vapor diffusion technique, mixing of protein in 10 mM HEPES, 150 mM NaCl, 0.5 mM FAD, and 5 mM MgCl2, pH 8.0, with crystallization solution containing 0.1 M sodium acetate, 25% PEG 4000, and 8% isopropyl alcohol for the wild-type enzyme, and 0.1 M sodium acetate, 22% PEG 4000, and 0.1 M HEPES buffer, pH 7.5, for the mutant H257G enzyme, 16°C, X-ray diffraction structure determination and analysis at 1.61 A and 1.92 A resolution, respectively
analysis of X-ray crystal structure of the Vibrio cholerae Nqr complex and structures of several purified components of the complex, PDB IDs 4U9S and 4P6V
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PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
E169K
K207A
site-directed mutagenesis, the mutant exhibits no detectable in vitro flavinylation activity
Y60A
site-directed mutagenesis, the engineered protein variant (Ftp_EcY60A) shows Mg2+-dependent FAD diphosphatase activity, but also retains its Mg2+-dependent FMN transferase (EC 2.7.1.180) activity on the protein substrate, indicating that the protein variant enzyme has dual activity
Y60N
H257G
H257T
site-directed mutagenesis, the mutant shows reduced activity compared to wild-type
additional information
E169K
site-directed mutagenesis of the probabale catalytic site residue, the Ftp_EcE169K protein variant does not show binding of FAD, inactive mutant
E169K
site-directed mutagenesis, mutation of the active-site residue results in loss of FAD binding capability
Y60N
site-directed mutagenesis, a single amino acid substitution converts it from an FAD-binding protein to a Mg2+-dependent FAD diphosphatase (Ftp_Tp-like)
Y60N
site-directed mutagenesis, the single amino acid substitution converts it from an FAD-binding protein to a Mg2+-dependent FAD pdiphosphatase (Ftp_Tp-like, EC 3.6.1.18). The Ftp_EcY60A protein variant binds FAD, rapidly hydrolyzes it, and the product FMN dissociates. But the mutant also retains its Mg2+-dependent FMN transferase (EC 2.7.1.180) activity on the protein substrate. As the site of attack for the FMN transferase reaction is the beta-phosphate of the FAD, and given the large distance between the two metals in the ADP-inhibited Ftp_EcY60N structure, it is reasonable to expect that only metal site 2 requires a Mg2+ ion for this activity
H257G
site-directed mutagenesis, the turnover rates of His257 mutants are significantly smaller than those of wild-type ApbE, and mutants show increased Km values for both substrates, the pKa of the catalytic residue (pKES1) increases by 2 pH units in the His257 mutants compared to wild-type, the mutant shows reduced activity compared to wild-type
H257G
site-directed mutagenesis, the mutant's flavin transfer activity is abolished. After reconstitution, the H257G shows a FAD:protein ratio nearly identical to the wild-type
additional information
replacement of non-Ala residues in the positions 0, -2, -3 and -6 by Ala, and Ala-1 by Val. Keeping in mind that the position +2 is occupied by a non-typical Gln in FRD, this residue is also replaced by Ala
additional information
-
replacement of non-Ala residues in the positions 0, -2, -3 and -6 by Ala, and Ala-1 by Val. Keeping in mind that the position +2 is occupied by a non-typical Gln in FRD, this residue is also replaced by Ala
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PURIFICATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
recombinant His-tagged wild-type ApbE and mutants from Escherichia coli by ultrafiltration, nickel affinity chromatography, cation chromatography, and gel filtration
recombinant His6-tagged wild-type ApbE and mutants from Escherichia coli by ultrafiltration, nickel affinity chromatography, cation chromatography, and gel filtration, to homogeneity
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CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
gene apbE, encoded in the nqr operon, recombinant expression of the gene alone or associated with the nqr operon in Escherichia coli strain ANN091. The Coexpression of Vibrio harveyi nqr operon and apbE gene in Escherichia coli fails to produce Na+-NQR capable of Na+-dependent quinone reduction. Production of Vibrio harveyi Na+-NQR capable of quinone reduction in Escherichia coli critically depends on the presence of the Vibrio harveyi ApbE and NqrM1 proteins
gene apbE, recombinant expression of His-tagged wild-type and mutant enzymes in Escherichia coli
gene apbE, recombinant overexpression of C-terminally His6-tagged wild-type and mutant enzymes in Escherichia coli. The recombinant protein does not contain the leader sequence (first 17 amino acids), and it is obtained as a cytosolic protein, although it is naturally localized in the periplasmic space
gene apbE1, frd-apbE operon, recombinant expression in Escherichia coli strain BW25113, ApbE and its target protein are coproduced in the cytoplasm of the recombinant cells
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REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Bertsova, Y.V.; Kostyrko, V.A.; Baykov, A.A.; Bogachev, A.V.
Localization-controlled specificity of FAD:threonine flavin transferases in Klebsiella pneumoniae and its implications for the mechanism of Na+-translocating NADH:quinone oxidoreductase
Biochim. Biophys. Acta
1837
1122-1129
2014
Klebsiella pneumoniae (B5XRA9), Klebsiella pneumoniae (B5XP00), Klebsiella pneumoniae, Klebsiella pneumoniae 342 (B5XRA9), Klebsiella pneumoniae 204 (B5XP00)
brenda
Bertsova, Y.V.; Fadeeva, M.S.; Kostyrko, V.A.; Serebryakova, M.V.; Baykov, A.A.; Bogachev, A.V.
Alternative pyrimidine biosynthesis protein ApbE is a flavin transferase catalyzing covalent attachment of FMN to a threonine residue in bacterial flavoproteins
J. Biol. Chem.
288
14276-14286
2013
Vibrio harveyi, Vibrio harveyi R3
brenda
Kostyrko, V.A.; Bertsova, Y.V.; Serebryakova, M.V.; Baykov, A.A.; Bogachev, A.V.
NqrM (DUF539) protein is required for maturation of bacterial Na+-translocating NADH:quinone oxidoreductase
J. Bacteriol.
198
655-663
2016
Vibrio harveyi (A0A3A1Q8E8), Vibrio harveyi, Vibrio harveyi ATCC 33843 (A0A3A1Q8E8)
brenda
Deka, R.K.; Brautigam, C.A.; Liu, W.Z.; Tomchick, D.R.; Norgard, M.V.
Molecular insights into the enzymatic diversity of flavin-trafficking protein (Ftp; formerly ApbE) in flavoprotein biogenesis in the bacterial periplasm
MicrobiologyOpen
5
21-38
2016
Treponema pallidum (O83774), Treponema pallidum, Escherichia coli (P0AB85), Escherichia coli, Vibrio cholerae serotype O1 (A5F5Y3), Vibrio cholerae serotype O1 O395 (A5F5Y3), Treponema pallidum Nichols (O83774), Vibrio cholerae serotype O1 ATCC 39541 (A5F5Y3), Vibrio cholerae serotype O1 Classical Ogawa 395 (A5F5Y3)
brenda
Bertsova, Y.V.; Serebryakova, M.V.; Anashkin, V.A.; Baykov, A.A.; Bogachev, A.V.
Mutational analysis of the flavinylation and binding motifs in two protein targets of the flavin transferase ApbE
FEMS Microbiol. Lett.
366
fnz252
2019
Klebsiella pneumoniae (A0A0C7KIE8), Klebsiella pneumoniae
brenda
Fang, X.; Osipiuk, J.; Chakravarthy, S.; Yuan, M.; Menzer, W.M.; Nissen, D.; Liang, P.; Raba, D.A.; Tuz, K.; Howard, A.J.; Joachimiak, A.; Minh, D.D.L.; Juarez, O.
Conserved residue His-257 of Vibrio cholerae flavin transferase ApbE plays a critical role in substrate binding and catalysis
J. Biol. Chem.
294
13800-13810
2019
Vibrio cholerae (A0A0F4FI39), Vibrio cholerae
brenda
Fang, X.; Liang, P.; Raba, D.; Rosas-Lemus, M.; Chakravarthy, S.; Tuz, K.; Juárez, O.
Kinetic characterization of Vibrio cholerae ApbE substrate specificity and regulatory mechanisms
PLoS ONE
12
e0186805
2017
Vibrio cholerae (A0A0F4FI39)
brenda
EXTERNAL LINKS (specific for EC-Number 2.7.1.180)
Transporter Classification Database (TCDB): 5.B.14.1.1
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