Information on EC 2.3.1.193 - tRNAMet cytidine acetyltransferase

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The expected taxonomic range for this enzyme is: Escherichia coli

EC NUMBER
COMMENTARY hide
2.3.1.193
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RECOMMENDED NAME
GeneOntology No.
tRNAMet cytidine acetyltransferase
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REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
[elongator tRNAMet]-cytidine34 + ATP + acetyl-CoA + H2O = CoA + [elongator tRNAMet]-N4-acetylcytidine34 + ADP + phosphate
show the reaction diagram
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SYSTEMATIC NAME
IUBMB Comments
acetyl-CoA:[elongator tRNAMet]-cytidine34 N4-acetyltransferase (ATP-hydrolysing)
The enzyme acetylates the wobble base cytidine34 of the CAU anticodon of elongation-specific tRNAMet. Escherichia coli TmcA strictly discriminates elongator tRNAMet from tRNAIle, which is structurally similar and has the same anticodon loop, mainly by recognizing the C27-G43 pair in the anticodon stem. The enzyme can use GTP in place of ATP for formation of N4-acetylcytidine [1].
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
malfunction
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a tmcA deletion strain does not show a growth defect. Thus, this modification does not appear to be required for faithful translation in an otherwise wild-type strain. A tmcA/dusC double deletion strain has a severe cold-sensitive growth defect
physiological function
posttranscriptional RNA modifications in the anticodon of transfer RNAs contributes to the high fidelity of protein synthesis. In eubacteria, two genome-encoded tRNA species bear the same CAU sequence as the anticodons, which are differentiated by modified cytidines at the wobble positions. The elongator tRNAMet accepts an acetyl moiety at the wobble base to form N4-acetylcytidine (ac4C): an inherent modification ensures precise decoding of the AUG codon by strengthening C-G base-pair interaction and concurrently preventing misreading of the near cognate AUA codon
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
[elongator tRNAMet]-cytidine34 + ATP + acetyl-CoA
[elongator tRNAMet]-N4-acetylcytidine34 + ADP + phosphate + coenzyme A
show the reaction diagram
[elongator tRNAMet]-cytidine34 + GTP + acetyl-CoA
[elongator tRNAMet]-N4-acetylcytidine34 + GDP + phosphate + coenzyme A
show the reaction diagram
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NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
[elongator tRNAMet]-cytidine34 + ATP + acetyl-CoA
[elongator tRNAMet]-N4-acetylcytidine34 + ADP + phosphate + coenzyme A
show the reaction diagram
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tRNAMet cytidine acetyltransferase acetylates the wobble base C34 of the elongation-specific tRNAMet. TmcA specifically recognizes the anticodon stem of tRNAMet, thus distinguishing between tRNAMet and tRNAIle2, which is structurally similar and has the same anticodon loop
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
additional information
additional information
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kinetic parameters for ATP-hydrolysis or GTP-hydrolysis
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TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
additional information
additional information
Escherichia coli
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kinetic parameters for ATP-hydrolysis or GTP-hydrolysis
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kcat/KM VALUE [1/mMs-1]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
additional information
additional information
Escherichia coli
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kinetic parameters for ATP-hydrolysis or GTP-hydrolysis
2
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
crystal structure of tRNAMet cytidine acetyltransferase from Escherichia coli complexed with two natural ligands, acetyl-CoA and ADP, at 2.35 A resolution. The structure reveals an idiosyncratic RNA helicase module fused with a GCN5-related N-acetyltransferase (GNAT) fold, which intimately crossinteract. It is proposed that an RNA helicase motor driven by ATP hydrolysis is used to deliver the wobble base to the active centre of the GNAT domain
Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
hexahistidine-tagged YpfI
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