Metabolic Modeling Tutorial
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BioCyc websites down
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Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
BioCyc websites down
12/28 - 12/31
for maintenance.
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
BioCyc websites down
12/28 - 12/31
for maintenance.
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
BioCyc websites down
12/28 - 12/31
for maintenance.
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
BioCyc websites down
12/28 - 12/31
for maintenance.
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MetaCyc Reaction: 2.7.7.79

Superclasses: Reactions Classified By Conversion Type Simple Reactions Chemical Reactions
Reactions Classified By Substrate Macromolecule Reactions Polynucleotide-Reactions RNA-Reactions tRNA-Reactions

EC Number: 2.7.7.79

Enzymes and Genes:
tRNAHis guanylyltransferase Inferred from experiment : THG1 ( Saccharomyces cerevisiae )

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

Mass balance status: Undetermined; a substrate lacks a chemical formula

Enzyme Commission Primary Name: tRNAHis guanylyltransferase

Enzyme Commission Synonyms: histidine tRNA guanylyltransferase, Thg1p (ambiguous), Thg1 (ambiguous)

Enzyme Commission Summary:
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, histidyl-tRNA ligase. The enzyme requires a divalent cation for activity [Pande91]. ATP activation is not required when the substrate contains a 5-triphosphate (ppp-tRNAHis) [Gu03].

The enzyme catalyzes two successive reactions.

The overall reaction is:

p-tRNAHis + ATP + GTP = pppGp-tRNAHis + AMP + diphosphate.

Citations: [Jahn91a, Placido10, Jackman08, Hyde10]

Gene-Reaction Schematic: ?

Relationship Links: BRENDA:EC:2.7.7.79 , ENZYME:EC:2.7.7.79 , IUBMB-ExplorEnz:EC:2.7.7.79

Credits:
Created 30-Jun-2011 by Kothari A , SRI International


References

Gu03: Gu W, Jackman JE, Lohan AJ, Gray MW, Phizicky EM (2003). "tRNAHis maturation: an essential yeast protein catalyzes addition of a guanine nucleotide to the 5' end of tRNAHis." Genes Dev 17(23);2889-901. PMID: 14633974

Hyde10: Hyde SJ, Eckenroth BE, Smith BA, Eberley WA, Heintz NH, Jackman JE, Doublie S (2010). "tRNA(His) guanylyltransferase (THG1), a unique 3'-5' nucleotidyl transferase, shares unexpected structural homology with canonical 5'-3' DNA polymerases." Proc Natl Acad Sci U S A 107(47);20305-10. PMID: 21059936

Jackman08: Jackman JE, Phizicky EM (2008). "Identification of critical residues for G-1 addition and substrate recognition by tRNA(His) guanylyltransferase." Biochemistry 47(16);4817-25. PMID: 18366186

Jahn91a: Jahn D, Pande S (1991). "Histidine tRNA guanylyltransferase from Saccharomyces cerevisiae. II. Catalytic mechanism." J Biol Chem 266(34);22832-6. PMID: 1660462

Pande91: Pande S, Jahn D, Soll D (1991). "Histidine tRNA guanylyltransferase from Saccharomyces cerevisiae. I. Purification and physical properties." J Biol Chem 266(34);22826-31. PMID: 1660461

Placido10: Placido A, Sieber F, Gobert A, Gallerani R, Giege P, Marechal-Drouard L (2010). "Plant mitochondria use two pathways for the biogenesis of tRNAHis." Nucleic Acids Res 38(21);7711-7. PMID: 20660484


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 18.5 on Mon Dec 22, 2014, biocyc13.