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Information on EC 2.7.7.79 - tRNAHis guanylyltransferase
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2.7.7.79 tRNAHis guanylyltransferaseIUBMB Comments
In eukarya an additional guanosine residue is added post-transcriptionally to the 5'-end of tRNAHis molecules. The addition occurs opposite a universally conserved adenosine73 and is thus the result of a non-templated 3'-5' addition reaction. The additional guanosine residue is an important determinant for aminoacylation by EC 6.1.1.21, histidine---tRNA ligase.The enzyme requires a divalent cation for activity . ATP activation is not required when the substrate contains a 5'-triphosphate (ppp-tRNAHis) .
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Word Map
- 2.7.7.79
- guanosine
- polymerases
- polymerization
-
histidyl-trna
- aminoacylation
-
fidelity
-
anticodon
-
post-transcriptionally
-
watson-crick
-
template-dependent
-
nucleotidyl
-
genome-encoded
- methanosarcina
- ntp
- acetivorans
-
phosphodiester
- thuringiensis
- medicine
The enzyme appears in viruses and cellular organisms
Reaction Schemes
p-tRNAHis
+
+
+
=
pGp-tRNAHis
+
+
2
p-tRNAHis
+
=
App-tRNAHis
+
App-tRNAHis
+
=
pppGp-tRNAHis
+
Synonyms
trna(his) guanylyltransferase, thg1l, trnahis guanylyltransferase, hsthg1, thg1p, mathg1, hthg1, bttlp, histidine trna guanylyltransferase, pathg1, 
more
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SYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
BtTLP
CaThg1
DdiTLP3
Igni_0485
IhTLP
MxTLP
PaThg1
PaTLP
RBTH_06728
ScThg1
THG1
Thg1 domain-containing protein
Thg1-like-protein
TLP
tRNA(His) guanylyltransferase
tRNA(His)-5'-guanylyltransferase (Thg1) like protein
UniProt
Thg1 domain-containing protein
UniProt
-
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
pppGp-tRNAHis + H2O = pGp-tRNAHis + diphosphate
(1c)
-
-
-
App-tRNAHis + GTP = pppGp-tRNAHis + AMP
-
-
-
-
p-tRNAHis + ATP + GTP + H2O = pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
p-tRNAHis + ATP + GTP + H2O = pGp-tRNAHis + AMP + 2 diphosphate
-
-
-
-
p-tRNAHis + ATP = App-tRNAHis + diphosphate
-
-
-
-
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SYSTEMATIC NAME
IUBMB Comments
p-tRNAHis:GTP guanylyltransferase (ATP-hydrolysing)
In eukarya an additional guanosine residue is added post-transcriptionally to the 5'-end of tRNAHis molecules. The addition occurs opposite a universally conserved adenosine73 and is thus the result of a non-templated 3'-5' addition reaction. The additional guanosine residue is an important determinant for aminoacylation by EC 6.1.1.21, histidine---tRNA ligase.The enzyme requires a divalent cation for activity [2]. ATP activation is not required when the substrate contains a 5'-triphosphate (ppp-tRNAHis) [3].
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SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
mt-tRNALeuDelta+2 + GTP
? + diphosphate
substrate mimics the presumed in vivo substrate for 5'-end repair, in which the two 5'-mismatched nucleotides have been removed and the resulting tRNA transcript begins with G+3. TLP1 and TLP2 catalyse robust addition of the missing 5'-G nucleotides to this substrate
-
-
?
p-ctRNAHis + ATP + GTP + H2O
pGp-ctRNAHis + AMP + 2 diphosphate
cytoplasmic tRNAHis
-
-
?
p-mtRNAHis + ATP + GTP + H2O
pGp-mtRNAHis + AMP + 2 diphosphate
mitochondrial tRNAHis
-
-
?
p-tRNAHis + ATP + 7-deaza-GTP + H2O
p-7-deaza-Gp-tRNAHis + AMP + 2 diphosphate
-
-
-
?
p-tRNAHis + ATP + dGTP
?
dGTP is almost as efficient as GTP for the guanylylation process. While GDP still serves for the enzymatic reaction, GMP is accepted very poorly by the enzyme
-
-
?
p-tRNAHis + ATP + GDP
?
dGTP is almost as efficient as GTP for the guanylylation process. While GDP still serves for the enzymatic reaction, GMP is accepted very poorly by the enzyme
-
-
?
p-tRNAHis + ATP + GTP
pppG-p-tRNAHis + AMP + diphosphate
the extra nucleotide in position -1 of mitochondrial and eukaryotic cytoplasmic tRNAHis molecules is added posttranscriptionally to the 5' end of the tRNA by a histidine-tRNA specific guanylyltransferase
-
-
?
p-tRNAHis + ATP + ITP + H2O
pIp-tRNAHis + AMP + 2 diphosphate
very high activity
-
-
?
p-tRNAHis + ATP + UTP + H2O
pUp-tRNAHis + AMP + 2 diphosphate
low activity
-
-
?
p-tRNAHis + dATP + GTP
pppGp-tRNAHis + dAMP + diphosphate
30% of the activity compared to ATP
-
-
?
p-tRNAHisC73 + ATP + 7-deaza-GTP + H2O
p-7-deaza-Gp-tRNAHisC73 + AMP + 2 diphosphate
T3C73 tRNAHis variant, low activity
-
-
?
p-tRNAHisC73 + ATP + GTP + H2O
pGp-tRNAHisC73 + AMP + 2 diphosphate
T3C73 tRNAHis variant, slightly reduced activity compared to wild-type T3A73 tRNAHis
-
-
?
p-tRNAHisC73 + ATP + ITP + H2O
pIp-tRNAHisC73 + AMP + 2 diphosphate
T3C73 tRNAHis variant, low activity
-
-
?
p-tRNAHisG73 + ATP + CTP + H2O
pCp-tRNAHisG73 + AMP + 2 diphosphate
T3G73 tRNAHis variant, no activity with CTP and wild-type T3A73 tRNAHis
-
-
?
p-tRNAHisG73 + ATP + GTP + H2O
pGp-tRNAHisG73 + AMP + 2 diphosphate
T3G73 tRNAHis variant, reduced activity compared to wild-type T3A73 tRNAHis
-
-
?
p-tRNAHisG73 + ATP + ITP + H2O
pIp-tRNAHisG73 + AMP + 2 diphosphate
T3G73 tRNAHis variant, reduced activity compared to wild-type T3A73 tRNAHis
-
-
?
p-tRNAHisU73 + ATP + 2-aminopurine + H2O
p-2.aminopurine-p-tRNAHisU73 + AMP + 2 diphosphate
T3U73 tRNAHis variant, activity is similar to wild-type T3A73 tRNAHis
-
-
?
p-tRNAHisU73 + ATP + GTP + H2O
pGp-tRNAHisU73 + AMP + 2 diphosphate
T3U73 tRNAHis variant, reduced activity compared to wild-type T3A73 tRNAHis
-
-
?
p-tRNAHisU73 + ATP + ITP + H2O
pIp-tRNAHisU73 + AMP + 2 diphosphate
T3U73 tRNAHis variant, low activity
-
-
?
ppp-tRNALeu + GTP
?
the D68A mutation causes a dramatic decrease in the rigorous specificity of Thg1 for tRNAHis. This single alteration enhances the kcat/KM for ppp-tRNALeu by 38-fold relative to that of wild-type Thg1
-
-
?
ppp-tRNAPhe + GTP
?
the D68A mutation causes a dramatic decrease in the rigorous specificity of Thg1 for tRNAHis. This single alteration enhances the kcat/KM for ppp-tRNAPhe by nearly 100-fold relative to that of wild-type Thg1
-
-
?
p-tRNAHis + ATP
App-tRNAHis + diphosphate
-
-
-
?
p-tRNAHis + ATP
App-tRNAHis + diphosphate
-
-
-
?
p-tRNAHis + ATP + 2-aminopurine + H2O
p-2-aminopurine-p-tRNAHis + AMP + 2 diphosphate
-
-
-
?
p-tRNAHis + ATP + 2-aminopurine + H2O
p-2-aminopurine-p-tRNAHis + AMP + 2 diphosphate
-
-
-
?
p-tRNAHis + ATP + 5'-triphosphorylated P4 + H2O
pUp-tRNAHis + AMP + 2 diphosphate
pppP4, neither ATP nor CTP is incorporated onto pppP4
-
-
?
p-tRNAHis + ATP + 5'-triphosphorylated P4 + H2O
pUp-tRNAHis + AMP + 2 diphosphate
pppP4, neither ATP nor CTP is incorporated onto pppP4
-
-
?
p-tRNAHis + ATP + GTP
pppGp-tRNAHis + AMP + diphosphate
-
overall reaction
-
?
p-tRNAHis + ATP + GTP
pppGp-tRNAHis + AMP + diphosphate
-
overall reaction
-
?
p-tRNAHis + ATP + GTP
pppGp-tRNAHis + AMP + diphosphate
-
-
-
?
p-tRNAHis + ATP + GTP
pppGp-tRNAHis + AMP + diphosphate
the G(-1) residue is both necessary and sufficient for aminoacylation of tRNA by histidyl-tRNA synthetase in vitro and is required for aminoacylation in vivo
-
-
?
p-tRNAHis + ATP + GTP
pppGp-tRNAHis + AMP + diphosphate
among all acceptor tRNAs in unfractionatedt RNA only tRNAHis is a substrate for the purified enzyme. tRNA from plant and prokaryotes are better substrates than mammalian and insect tRNAs
-
-
?
p-tRNAHis + ATP + GTP
pppGp-tRNAHis + AMP + diphosphate
during the first step ATP is cleaved to AMP and diphosphate creating adenylylated enzyme. In a second step the activated enzyme forms a stable complex with its cognate tRNA substrate. The 5'-phosphate of the tRNA is adenylylated by nucleotide transfer from the adenylylated guanylyltransferase to form A(5')pp(5') at the 5'-end of the tRNA. Finally, the 3'-hydroxyl of GTP adds to the activated 5' terminus of the tRNA with the release of AMP. dGTP is almost as efficient as GTP for the guanylylation process. While GDP still serves for the enzymatic reaction, GMP is accepted very poorly by the enzyme
-
-
?
p-tRNAHis + ATP + GTP
pppGp-tRNAHis + AMP + diphosphate
specific for tRNAHis. No activity with tRNAPhe. No ATP is required when ppp-tRNAHis is used as a substrate
-
-
?
p-tRNAHis + ATP + GTP
pppGp-tRNAHis + AMP + diphosphate
Thg1 is more than 10000-fold more selective for its cognate substrate tRNAHis than for the noncognate substrate tRNAPhe. Alteration of this anticodon in tRNAHis completely abrogates Thg1 activity, and the introduction of this GUG anticodon to tRNAPhe or tRNAGly results in significant Thg1 activity
-
-
?
p-tRNAHis + ATP + GTP
pppGp-tRNAHis + AMP + diphosphate
-
all tRNAHis possess an essential extra G1 guanosine residue at their 5' end. This extra guanylate residue can be generated via two different processes. In Escherichia coli and in chloroplasts, the G1 is genome-encoded and retained during tRNA maturation because of an unusual cleavage of the pre-tRNAHis at the (-1) position by RNase P. In Saccharomyces cerevisiae as well as in Drosophila melanogaster the G1 is not genome-encoded and must be post-transcriptionally added at the 5' terminus of the nuclear-encoded tRNAHis by a specific tRNAHis guanylyltransferase. In plant mitochondria, although trnH genes possess a G1 tRNAHis guanylyltransferase activity is present in plant mitochondria
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction, GTP is incorporated at the -1 position opposite the highly conserved A73 residue in eukaryotic tRNAHis
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction, GTP is incorporated at the -1 position opposite the highly conserved A73 residue in eukaryotic tRNAHis
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
-
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
-
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
-
-
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
-
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
-
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
overall reaction
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
-
-
-
?
p-tRNAHis + ATP + GTP + H2O
pGp-tRNAHis + AMP + 2 diphosphate
Saccharomyces cerevisiae ATCC 2045083
overall reaction
-
-
?
additional information
?
-
the TLP from Bacillus thuringiensis (BtTLP) can utilize GTP to activate the 5'-end of tRNAHis in vitro, whereas bona fide Thg1 enzymes are so far strictly ATP-dependent for catalyzing this reaction
-
-
-
additional information
?
-
when full-length tRNAHis (lacking the G-1 residue) is used as a substrate, TLP exhibits a strong preference for use of GTP over ATP for 5'-end activation. Product formation is extremely slow in the presence of only ATP. With a 5'-truncated substrate missing the +1 nucleotide, both ATP and GTP are used with relatively equal efficiency for activation
-
-
?
additional information
?
-
TLPs exhibit a strong preference for adding WC-base paired nucleotides to RNA substrates
-
-
-
additional information
?
-
when full-length tRNAHis (lacking the G-1 residue) is used as a substrate, TLP exhibits a strong preference for use of GTP over ATP for 5'-end activation. Product formation is extremely slow in the presence of only ATP. With a 5'-truncated substrate missing the +1 nucleotide, both ATP and GTP are used with relatively equal efficiency for activation
-
-
?
additional information
?
-
TLPs exhibit a strong preference for adding WC-base paired nucleotides to RNA substrates
-
-
-
additional information
?
-
the TLP from Bacillus thuringiensis (BtTLP) can utilize GTP to activate the 5'-end of tRNAHis in vitro, whereas bona fide Thg1 enzymes are so far strictly ATP-dependent for catalyzing this reaction
-
-
-
additional information
?
-
kinetic analysis and substrate specificity, overview. GTP can be directly conjugated with 5'-triphosphorylated tRNAHis without ATP activation. UTP is a poor substrate. The reaction efficiency of GTP addition is affected by the structure of the opposite base at position 73. No activity with ATP, 8-oxo-GTP, isoGTP, and 8-bromo-GTP instead of GTP. The activity with CTP, 2-aminopurine, 7-deaza-GTP, ITP, and UTP depends on the tRNAHIs substrate identity
-
-
-
additional information
?
-
Thg1 recognizes tRNAHis through its GUG anticodon, as demonstrated by the ability of Thg1 to add G-1 to a mutagenized tRNAPhe that has been altered to contain the His anticodon (tRNAPheGUG) and subsequently validated through a cocrystal structure of Candida albicans Thg1 in complex with tRNAPheGUG. The coordination of tRNA molecules occurs in a molar ratio of 4:2, where two tRNA molecules bind a Thg1 tetramer in parallel orientation, and each tRNA is coordinated by three subunits of the tetramer. The enzyme performs 3' to 5' or reverse polymerization
-
-
-
additional information
?
-
Thg1 recognizes tRNAHis through its GUG anticodon, as demonstrated by the ability of Thg1 to add G-1 to a mutagenized tRNAPhe that has been altered to contain the His anticodon (tRNAPheGUG) and subsequently validated through a cocrystal structure of Candida albicans Thg1 in complex with tRNAPheGUG. The coordination of tRNA molecules occurs in a molar ratio of 4:2, where two tRNA molecules bind a Thg1 tetramer in parallel orientation, and each tRNA is coordinated by three subunits of the tetramer. The enzyme performs 3' to 5' or reverse polymerization
-
-
-
additional information
?
-
kinetic analysis and substrate specificity, overview. GTP can be directly conjugated with 5'-triphosphorylated tRNAHis without ATP activation. UTP is a poor substrate. The reaction efficiency of GTP addition is affected by the structure of the opposite base at position 73. No activity with ATP, 8-oxo-GTP, isoGTP, and 8-bromo-GTP instead of GTP. The activity with CTP, 2-aminopurine, 7-deaza-GTP, ITP, and UTP depends on the tRNAHIs substrate identity
-
-
-
additional information
?
-
TLPs exhibit a strong preference for adding WC-base paired nucleotides to RNA substrates
-
-
-
additional information
?
-
human Thg1 (hThg1) catalyzes the G-1 addition reaction for both human ctRNAHis and mtRNAHis through recognition of the anticodon. While hThg1 catalyzes consecutive GTP additions to mtRNAHis in vitr (consecutive G-2 and G-3 addition to pppG-1-hmtRNAHis), it does not exhibit any activity toward mature pG-1-mtRNAHis. hThg1 can add a GMP directly to the 5'-terminus of mtRNAHis in a template-dependent manner, but not to ctRNAHis. Acceleration of the diphosphate removal activity before or after the G-1 addition reaction is a key feature of hThg1 for maintaining a normal 5'-terminus of mtRNAHis in human mitochondria. The GUG to GAA conversion completely abolishes the ability of hThg1 to catalyze the adenylylation of both tRNAs, anticodon variants of hmtRNAHisGAA and hctRNAHis GAA, respetively, suggesting that hThg1 recognizes both of them in a His anticodon-dependent manner. The mobility of mtRNAHis is significantly faster than that of hctRNAHis on a native-PAGE gel, further suggesting a structural difference between them that is consistent with secondary structure predictions
-
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-
additional information
?
-
-
human Thg1 (hThg1) catalyzes the G-1 addition reaction for both human ctRNAHis and mtRNAHis through recognition of the anticodon. While hThg1 catalyzes consecutive GTP additions to mtRNAHis in vitr (consecutive G-2 and G-3 addition to pppG-1-hmtRNAHis), it does not exhibit any activity toward mature pG-1-mtRNAHis. hThg1 can add a GMP directly to the 5'-terminus of mtRNAHis in a template-dependent manner, but not to ctRNAHis. Acceleration of the diphosphate removal activity before or after the G-1 addition reaction is a key feature of hThg1 for maintaining a normal 5'-terminus of mtRNAHis in human mitochondria. The GUG to GAA conversion completely abolishes the ability of hThg1 to catalyze the adenylylation of both tRNAs, anticodon variants of hmtRNAHisGAA and hctRNAHis GAA, respetively, suggesting that hThg1 recognizes both of them in a His anticodon-dependent manner. The mobility of mtRNAHis is significantly faster than that of hctRNAHis on a native-PAGE gel, further suggesting a structural difference between them that is consistent with secondary structure predictions
-
-
-
additional information
?
-
the enzyme performs 3' to 5' or reverse polymerization
-
-
-
additional information
?
-
-
Thg1 activity assay with 5'-triphosphorylated tRNAHis
-
-
-
additional information
?
-
IhTLP is catalytically active in vitro, and catalyzes a significant tRNA repair reaction in vitro, adding up to 13 nucleotides to restore a truncated tRNAHis
-
-
-
additional information
?
-
the enzyme is active in an in vitro activity assay with radiolabelled Escherichia coli tRNAHisDG-1 and recombinant wild-type IhThg1 enzyme. IhThg1 displays reduced enzyme activity with yeast tRNAHisDG-1, which encodes an A73 discriminator base in compared to Escherichia coli tRNAHisDG-1 with a C73 discriminator base. Radioactive product formation is observed in the presence or absence of ATP, suggesting that IhThg1 does not require ATP-dependent activation, but can utilize GTP, as observed for other archaeal-type Thg1 enzymes. . Substrate specificity analysis with tRNAHis substrates differing in the discrimination position 73, and different nucleotides, i.e. radiolabelled GTP and unlabeled GTP, ATP, UTP, and CTP, analysis of Thg1 sequence determinants for extended reverse polymerization. IhThg1 is active despite lacking conserved RNA recognition motifs. The palm domain of Thg1 is sufficient for catalytic activity
-
-
-
additional information
?
-
-
the enzyme is active in an in vitro activity assay with radiolabelled Escherichia coli tRNAHisDG-1 and recombinant wild-type IhThg1 enzyme. IhThg1 displays reduced enzyme activity with yeast tRNAHisDG-1, which encodes an A73 discriminator base in compared to Escherichia coli tRNAHisDG-1 with a C73 discriminator base. Radioactive product formation is observed in the presence or absence of ATP, suggesting that IhThg1 does not require ATP-dependent activation, but can utilize GTP, as observed for other archaeal-type Thg1 enzymes. . Substrate specificity analysis with tRNAHis substrates differing in the discrimination position 73, and different nucleotides, i.e. radiolabelled GTP and unlabeled GTP, ATP, UTP, and CTP, analysis of Thg1 sequence determinants for extended reverse polymerization. IhThg1 is active despite lacking conserved RNA recognition motifs. The palm domain of Thg1 is sufficient for catalytic activity
-
-
-
additional information
?
-
IhTLP is catalytically active in vitro, and catalyzes a significant tRNA repair reaction in vitro, adding up to 13 nucleotides to restore a truncated tRNAHis
-
-
-
additional information
?
-
IhTLP is catalytically active in vitro, and catalyzes a significant tRNA repair reaction in vitro, adding up to 13 nucleotides to restore a truncated tRNAHis
-
-
-
additional information
?
-
IhTLP is catalytically active in vitro, and catalyzes a significant tRNA repair reaction in vitro, adding up to 13 nucleotides to restore a truncated tRNAHis
-
-
-
additional information
?
-
enzyme activity assay with purified recombinant palm domains from Methanosarcina acetivorans Thg1 (MaPalm, amino acids 1-141) incubated with radiolabelled Escherichia coli tRNAHisDELTAG-1 and GTP. Substrate specificity analysis with tRNAHis substrates differing in the discrimination position 73, and different nucleotides, i.e. radiolabelled GTP and unlabeled GTP, ATP, UTP, and CTP, analysis of Thg1 sequence determinants for extended reverse polymerization. The palm domain of Thg1 is sufficient for catalytic activity
-
-
-
additional information
?
-
-
enzyme activity assay with purified recombinant palm domains from Methanosarcina acetivorans Thg1 (MaPalm, amino acids 1-141) incubated with radiolabelled Escherichia coli tRNAHisDELTAG-1 and GTP. Substrate specificity analysis with tRNAHis substrates differing in the discrimination position 73, and different nucleotides, i.e. radiolabelled GTP and unlabeled GTP, ATP, UTP, and CTP, analysis of Thg1 sequence determinants for extended reverse polymerization. The palm domain of Thg1 is sufficient for catalytic activity
-
-
-
additional information
?
-
the TLP from Myxococcus xanthus (MxTLP) can utilize GTP to activate the 5'-end of tRNAHis in vitro, whereas bona fide Thg1 enzymes are so far strictly ATP-dependent for catalyzing this reaction
-
-
-
additional information
?
-
the TLP from Myxococcus xanthus (MxTLP) can utilize GTP to activate the 5'-end of tRNAHis in vitro, whereas bona fide Thg1 enzymes are so far strictly ATP-dependent for catalyzing this reaction
-
-
-
additional information
?
-
enzyme activity assay with purified recombinant palm domains from Pyrobaculum aerophilum Thg1 (PaPalm, amino acids 1-150) incubated with radiolabelled Escherichia coli tRNAHisDELTAG-1 and GTP. PaThg1 repairs truncated tRNA substrates. Substrate specificity analysis with tRNAHis substrates differing in the discrimination position 73, and different nucleotides, i.e. radiolabelled GTP and unlabeled GTP, ATP, UTP, and CTP, analysis of Thg1 sequence determinants for extended reverse polymerization. PaThg1 adds a single nucleotide to the guide RNAs and also to the control hammerhead ribozyme RNAs in the presence or absence of target RNAs. The palm domain of Thg1 is sufficient for catalytic activity
-
-
-
additional information
?
-
-
enzyme activity assay with purified recombinant palm domains from Pyrobaculum aerophilum Thg1 (PaPalm, amino acids 1-150) incubated with radiolabelled Escherichia coli tRNAHisDELTAG-1 and GTP. PaThg1 repairs truncated tRNA substrates. Substrate specificity analysis with tRNAHis substrates differing in the discrimination position 73, and different nucleotides, i.e. radiolabelled GTP and unlabeled GTP, ATP, UTP, and CTP, analysis of Thg1 sequence determinants for extended reverse polymerization. PaThg1 adds a single nucleotide to the guide RNAs and also to the control hammerhead ribozyme RNAs in the presence or absence of target RNAs. The palm domain of Thg1 is sufficient for catalytic activity
-
-
-
additional information
?
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enzyme activity assay with purified recombinant palm domains from Pyrobaculum aerophilum Thg1 (PaPalm, amino acids 1-150) incubated with radiolabelled Escherichia coli tRNAHisDELTAG-1 and GTP. PaThg1 repairs truncated tRNA substrates. Substrate specificity analysis with tRNAHis substrates differing in the discrimination position 73, and different nucleotides, i.e. radiolabelled GTP and unlabeled GTP, ATP, UTP, and CTP, analysis of Thg1 sequence determinants for extended reverse polymerization. PaThg1 adds a single nucleotide to the guide RNAs and also to the control hammerhead ribozyme RNAs in the presence or absence of target RNAs. The palm domain of Thg1 is sufficient for catalytic activity
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additional information
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enzyme activity assay with purified recombinant palm domains from Pyrobaculum aerophilum Thg1 (PaPalm, amino acids 1-150) incubated with radiolabelled Escherichia coli tRNAHisDELTAG-1 and GTP. PaThg1 repairs truncated tRNA substrates. Substrate specificity analysis with tRNAHis substrates differing in the discrimination position 73, and different nucleotides, i.e. radiolabelled GTP and unlabeled GTP, ATP, UTP, and CTP, analysis of Thg1 sequence determinants for extended reverse polymerization. PaThg1 adds a single nucleotide to the guide RNAs and also to the control hammerhead ribozyme RNAs in the presence or absence of target RNAs. The palm domain of Thg1 is sufficient for catalytic activity
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additional information
?
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enzyme activity assay with purified recombinant palm domains from Pyrobaculum aerophilum Thg1 (PaPalm, amino acids 1-150) incubated with radiolabelled Escherichia coli tRNAHisDELTAG-1 and GTP. PaThg1 repairs truncated tRNA substrates. Substrate specificity analysis with tRNAHis substrates differing in the discrimination position 73, and different nucleotides, i.e. radiolabelled GTP and unlabeled GTP, ATP, UTP, and CTP, analysis of Thg1 sequence determinants for extended reverse polymerization. PaThg1 adds a single nucleotide to the guide RNAs and also to the control hammerhead ribozyme RNAs in the presence or absence of target RNAs. The palm domain of Thg1 is sufficient for catalytic activity
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additional information
?
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enzyme activity assay with purified recombinant palm domains from Pyrobaculum aerophilum Thg1 (PaPalm, amino acids 1-150) incubated with radiolabelled Escherichia coli tRNAHisDELTAG-1 and GTP. PaThg1 repairs truncated tRNA substrates. Substrate specificity analysis with tRNAHis substrates differing in the discrimination position 73, and different nucleotides, i.e. radiolabelled GTP and unlabeled GTP, ATP, UTP, and CTP, analysis of Thg1 sequence determinants for extended reverse polymerization. PaThg1 adds a single nucleotide to the guide RNAs and also to the control hammerhead ribozyme RNAs in the presence or absence of target RNAs. The palm domain of Thg1 is sufficient for catalytic activity
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additional information
?
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enzyme activity assay with purified recombinant palm domains from Pyrobaculum aerophilum Thg1 (PaPalm, amino acids 1-150) incubated with radiolabelled Escherichia coli tRNAHisDELTAG-1 and GTP. PaThg1 repairs truncated tRNA substrates. Substrate specificity analysis with tRNAHis substrates differing in the discrimination position 73, and different nucleotides, i.e. radiolabelled GTP and unlabeled GTP, ATP, UTP, and CTP, analysis of Thg1 sequence determinants for extended reverse polymerization. PaThg1 adds a single nucleotide to the guide RNAs and also to the control hammerhead ribozyme RNAs in the presence or absence of target RNAs. The palm domain of Thg1 is sufficient for catalytic activity
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additional information
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in vivo Thg1 catalyzes 3'5' polymerization on tRNAHisC73, but not on tRNAHisA73
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?
additional information
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in vivo Thg1 catalyzes 3'5' polymerization on tRNAHisC73, but not on tRNAHisA73
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?
additional information
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the enzyme also catalyzes 3'-5' extension of a polynucleotude chain by multiple nucleotides. Unlike the addition of G(-1), the reverse polymerisation activity is template-dependent, recognizing G*C WatsonCrick base pairs. Moreover, reverse polymerization is not specific for tRNAHis or for starting at the (-1) position of tRNA, provided that the activated (triphosphorylated) form of the tRNA substrate is used in the assays
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?
additional information
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retention of the 5'-triphosphate is correlated with efficient 3'-5' reverse polymerization. The intrinsic rate of removal of diphosphate from the G-1 residue of base-paired tRNAHis substrates is slow. Rates of diphosphate removal depend on the identity of the NTP included in reactions. The GTP 3'-OH is required to stimulate diphosphate removal
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additional information
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retention of the 5'-triphosphate is correlated with efficient 3'-5' reverse polymerization. The intrinsic rate of removal of diphosphate from the G-1 residue of base-paired tRNAHis substrates is slow. Rates of diphosphate removal depend on the identity of the NTP included in reactions. The GTP 3'-OH is required to stimulate diphosphate removal
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?
additional information
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the enzyme performs 3' to 5' or reverse polymerization
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additional information
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the GTP molecule is clearly bound at the active site, coordinating with two magnesium ions
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additional information
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the GTP molecule is clearly bound at the active site, coordinating with two magnesium ions
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additional information
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tRNAHis guanylyltransferase clearly prefers a substrate carrying a CCA terminus. The 3'-CCA triplet and a discriminator position A73 act as positive elements for G-1 incorporation, ensuring the fidelity of G-1 addition. On the substrate lacking the CCA-end (tRNAHisDELTACCA), the enzyme is less efficient
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additional information
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tRNAHis guanylyltransferase clearly prefers a substrate carrying a CCA terminus. The 3'-CCA triplet and a discriminator position A73 act as positive elements for G-1 incorporation, ensuring the fidelity of G-1 addition. On the substrate lacking the CCA-end (tRNAHisDELTACCA), the enzyme is less efficient
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additional information
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the enzyme performs 3' to 5' or reverse polymerization
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additional information
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tRNAHis guanylyltransferase clearly prefers a substrate carrying a CCA terminus. The 3'-CCA triplet and a discriminator position A73 act as positive elements for G-1 incorporation, ensuring the fidelity of G-1 addition. On the substrate lacking the CCA-end (tRNAHisDELTACCA), the enzyme is less efficient
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additional information
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Saccharomyces cerevisiae ATCC 2045083
the GTP molecule is clearly bound at the active site, coordinating with two magnesium ions
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NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
p-ctRNAHis + ATP + GTP + H2O
pGp-ctRNAHis + AMP + 2 diphosphate
cytoplasmic tRNAHis
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?
p-mtRNAHis + ATP + GTP + H2O
pGp-mtRNAHis + AMP + 2 diphosphate