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Information on EC 6.6.1.1 - magnesium chelatase and Organism(s) Synechocystis sp. and UniProt Accession P51634

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EC Tree
     6 Ligases
         6.6 Forming nitrogen—metal bonds
             6.6.1 Forming coordination complexes
                6.6.1.1 magnesium chelatase
IUBMB Comments
This is the first committed step of chlorophyll biosynthesis and is a branchpoint of two major routes in the tetrapyrrole pathway.
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This record set is specific for:
Synechocystis sp.
UNIPROT: P51634
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The taxonomic range for the selected organisms is: Synechocystis sp.
The expected taxonomic range for this enzyme is: Bacteria, Eukaryota, Archaea
Synonyms
magnesium chelatase, mg-chelatase, mg chelatase, chli1, xantha-f, abar/chlh, magnesium-chelatase, mg-chelatase h, chelatase h subunit, chli protein, more
SYNONYM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
ChlH
-
subunit of the magnesium chelatase
magnesium chelatase
-
-
magnesium-chelatase
-
-
-
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magnesium-protoporphyrin chelatase
-
-
-
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magnesium-protoporphyrin IX chelatase
-
-
-
-
Mg-chelatase
Mg-protoporphyrin IX magnesio-lyase
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-
-
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protoporphyrin IX magnesium-chelatase
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-
-
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protoporphyrin IX Mg-chelatase
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-
-
-
REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
ATP + protoporphyrin IX + Mg2+ + H2O = ADP + phosphate + Mg-protoporphyrin IX + 2 H+
show the reaction diagram
ATP + protoporphyrin IX + Mg2+ + H2O = ADP + phosphate + Mg-protoporphyrin IX + 2 H+
show the reaction diagram
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
Ligation
-
-
-
-
SYSTEMATIC NAME
IUBMB Comments
Mg-protoporphyrin IX magnesium-lyase
This is the first committed step of chlorophyll biosynthesis and is a branchpoint of two major routes in the tetrapyrrole pathway.
CAS REGISTRY NUMBER
COMMENTARY hide
9074-88-8
-
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
ATP + protoporphyrin IX + Mg2+ + H2O
ADP + phosphate + Mg-protoporphyrin IX + H+
show the reaction diagram
-
-
?
ATP + deuteroporphyrin + Mg2+ + H2O
ADP + phosphate + Mg-deuteroporphyrin + H+
show the reaction diagram
-
-
-
-
?
ATP + deuteroporphyrin IX + Mg2+ + H2O
ADP + phosphate + Mg-deuteroporphyrin IX + H+
show the reaction diagram
ATP + protoporphyrin IX + Mg2+ + H2O
ADP + phosphate + Mg-protoporphyrin IX + H+
show the reaction diagram
NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
ATP + protoporphyrin IX + Mg2+ + H2O
ADP + phosphate + Mg-protoporphyrin IX + H+
show the reaction diagram
-
-
?
ATP + deuteroporphyrin IX + Mg2+ + H2O
ADP + phosphate + Mg-deuteroporphyrin IX + H+
show the reaction diagram
-
magnesium chelatase catalyzes the first committed step in chlorophyll biosynthesis
-
-
?
ATP + protoporphyrin IX + Mg2+ + H2O
ADP + phosphate + Mg-protoporphyrin IX + H+
show the reaction diagram
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
N-ethylmaleimide
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binds to ChlI subunit and inhibits its ATPase activity. The ChlI-ChlD-ATP complex forms but cannot catalyse magnesium chelation. Prior incubation with MgATP2- affords protection. Full protection can also be obtained with 5 mM ATP or 5 mM ADP alone
ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
Gun4
-
addition of Gun4 up to 0.0005 mM stimulates the wild type enzyme 2-3fold. Up to 0.001 mM Gun4 resurrects the inactive gun5 and cch mutant Mg-chelatase reactions to the level seen in the wild type with no Gun4 present, particularly in the case of mutant gun5
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.45
ATP
-
-
0.00099 - 0.008
deuteroporphyrin
0.0032
deuteroporphyrin IX
-
-
TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.0009 - 0.0067
ATP
0.0013 - 0.0188
deuteroporphyrin
0.013
deuteroporphyrin IX
-
-
0.0028 - 0.0083
Mg2+
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
7.7
-
assay at
TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
34
-
assay at
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
-
Uniprot
Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
metabolism
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magnesium chelatase catalyses the first committed step of chlorophyll biosynthesis
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
60000
x * 60000, calculation from sequence of cDNA, D subunit
148000
39000
-
1 * 148000 + 1 * 39000 + 1 * 73000, subunits ChlH, ChlI and ChlD
73000
-
1 * 148000 + 1 * 39000 + 1 * 73000, subunits ChlH, ChlI and ChlD
SUBUNIT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
?
x * 60000, calculation from sequence of cDNA, D subunit
heterotrimer
-
1 * 148000 + 1 * 39000 + 1 * 73000, subunits ChlH, ChlI and ChlD
additional information
PROTEIN VARIANTS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
A942V
-
the (gun5) mutation abolishes activity of Mg-chelatase subunit H. Increasing the ChlH concentration up to 0.02 mM restores approximately 50% activity in the presence of the gun5 mutation. The addition of Gun4 restores Mg-chelatase activity of the gun5 mutant enzyme
E152Q
-
mutation in the AAA+ domain of ChlD binds to ChlI. Mutant shows low activity but assembles into complexes much like wild-type. Mutant shows 25% of wild-type activity. kcat/K0.5 for Mg2+ is 30% of wild-type. kcat and Km for deuteroporphyrin are reduced to the same extent
K49A
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mutation in the AAA+ domain of ChlD binds to ChlI. Mutant shows no activity. Mutant forms detecable amount of ChlID complexes
P595L
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the (cch) mutation abolishes activity of Mg-chelatase subunit H. Increasing the ChlH concentration up to 0.02 mM fully restores activity in the presence of the cch mutation. The addition of Gun4 restores Mg-chelatase activity of the cch mutant enzyme
R208A
-
mutation in the AAA+ domain of ChlD binds to ChlI. Mutant shows reduced binding affinity to ChlI.Mutant shows 50% of wild-type activity (least impaired mutant). Effect on substrate handling is modest compared to wild-type. Specifictiy constants for Mg2+ and porphyrin are 70% of wild-type
R289A
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mutation in the AAA+ domain of ChlD binds to ChlI. Mutant shows reduced binding affinity to ChlI. Mutant shows 13% of wild-type activity. Mutant does not show a cooperative response to MgATP2- and has much weaker specificity toward Mg2+ than wild-type. Mutant has a lower specificity toward free porphyrin than wild-type
additional information
-
Synechocystis chelatase tolerates substitution of individual subunits with their Thermosynechococcus equivalents to produce hybrid enzymes.The heterologous complex is much less active than either of the two parent enzymes
PURIFICATION (Commentary)
ORGANISM
UNIPROT
LITERATURE
mutant enzymes are purified by Ni2+ affinity column chromatography
-
using Ni-NTA chromatography
-
CLONED (Commentary)
ORGANISM
UNIPROT
LITERATURE
expressed in Escherichia coli as a His-tagged fusion protein
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expression in Escherichia coli
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mutant enzymes are expressed in Escherichia coli
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REF.
AUTHORS
TITLE
JOURNAL
VOL.
PAGES
YEAR
ORGANISM (UNIPROT)
PUBMED ID
SOURCE
Walker, C.J.; Willows, R.D.
Mechanism and regulation of Mg-chelatase
Biochem. J.
327
321-333
1997
Arabidopsis thaliana, Cucumis sativus, Hordeum vulgare, Pisum sativum, Rhodobacter capsulatus, Cereibacter sphaeroides, Synechocystis sp. (P51634)
Manually annotated by BRENDA team
Reid, J.D.; Hunter, C.N.
Current understanding of the function of magnesium chelatase
Biochem. Soc. Trans.
30
643-645
2002
Synechocystis sp., Arabidopsis thaliana
Manually annotated by BRENDA team
Karger, G.A.; Reid, J.D.; Hunter, C.N.
Characterization of the binding of deuteroporphyrin IX to the magnesium chelatase H subunit and spectroscopic properties of the complex
Biochemistry
40
9291-9299
2001
Synechocystis sp., Cereibacter sphaeroides
Manually annotated by BRENDA team
Jensen, P.E.; Reid, J.D.; Hunter, C.N.
Modification of cysteine residues in the ChlI and ChlH subunits of magnesium chelatase results in enzyme inactivation
Biochem. J.
352
435-441
2000
Synechocystis sp.
Manually annotated by BRENDA team
Shepherd, M.; McLean, S.; Hunter, C.N.
Kinetic basis for linking the first two enzymes of chlorophyll biosynthesis
FEBS J.
272
4532-4539
2005
Synechocystis sp.
Manually annotated by BRENDA team
Reid, J.D.; Hunter, C.N.
Magnesium-dependent ATPase activity and cooperativity of magnesium chelatase from Synechocystis sp. PCC6803
J. Biol. Chem.
279
26893-26899
2004
Synechocystis sp.
Manually annotated by BRENDA team
Viney, J.; Davison, P.A.; Hunter, C.N.; Reid, J.D.
Direct measurement of metal-ion chelation in the active site of the AAA(+) ATPase magnesium chelatase
Biochemistry
46
12788-12794
2007
Synechocystis sp.
Manually annotated by BRENDA team
Davison, P.A.; Hunter, C.N.
Abolition of magnesium chelatase activity by the gun5 mutation and reversal by Gun4
FEBS Lett.
585
183-186
2011
Synechocystis sp.
Manually annotated by BRENDA team
Adams, N.B.; Marklew, C.J.; Brindley, A.A.; Hunter, C.N.; Reid, J.D.
Characterization of the magnesium chelatase from Thermosynechococcus elongatus
Biochem. J.
457
163-170
2014
Synechocystis sp., Thermosynechococcus vestitus
Manually annotated by BRENDA team
Adams, N.B.; Reid, J.D.
The allosteric role of the AAA+ domain of ChlD protein from the magnesium chelatase of synechocystis species PCC 6803
J. Biol. Chem.
288
28727-28732
2013
Synechocystis sp.
Manually annotated by BRENDA team