Document Detail


Identification of the rate-determining step of tRNA-guanine transglycosylase from Escherichia coli.
MedLine Citation:
PMID:  19874048     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The modified RNA base queuine [7-(4,5-cis-dihydroxy-1-cyclopenten-3-ylaminomethyl)-7-deazaguanine] is present in tRNA because of a unique base-exchange process catalyzed by tRNA-guanine transglycosylase (TGT). Previous studies have suggested the intermediacy of a covalent TGT-RNA complex. To exist on the reaction pathway, this covalent complex must be both chemically and kinetically competent. Chemical competence has been demonstrated by the crystal structure studies of Xie et al. [(2003) Nat. Struct. Biol. 10, 781-788]; however, evidence of kinetic competence had not yet been established. The studies reported here unequivocally demonstrate that the TGT-RNA covalent complex is kinetically capable of occurring on the TGT reaction pathway. These studies further suggest that dissociation of product RNA from the enzyme is overall rate-limiting in the steady state. Interestingly, studies comparing RNA with a 2'-deoxyriboside at the site of modification suggest a role for the 2'-hydroxyl group in stabilizing the growing negative charge on the nucleophilic aspartate (264) as the glycosidic bond to the aspartate is broken during the breakdown of the covalent complex.
Authors:
George A Garcia; Stephanie M Chervin; Jeffrey D Kittendorf
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biochemistry     Volume:  48     ISSN:  1520-4995     ISO Abbreviation:  Biochemistry     Publication Date:  2009 Dec 
Date Detail:
Created Date:  2009-11-25     Completed Date:  2009-12-17     Revised Date:  2014-09-16    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  United States    
Other Details:
Languages:  eng     Pagination:  11243-51     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Aspartic Acid / chemistry,  metabolism
Binding Sites
Crystallography, X-Ray
Deoxyribose / chemistry,  metabolism
Escherichia coli / enzymology*
Glycosides / chemistry,  metabolism
Kinetics
Models, Chemical
Pentosyltransferases / chemistry,  metabolism*
RNA / chemistry,  metabolism
Substrate Specificity
Grant Support
ID/Acronym/Agency:
GM065489/GM/NIGMS NIH HHS; GM07767/GM/NIGMS NIH HHS; R01 GM065489/GM/NIGMS NIH HHS; R01 GM065489-04/GM/NIGMS NIH HHS
Chemical
Reg. No./Substance:
0/Glycosides; 30KYC7MIAI/Aspartic Acid; 533-67-5/Deoxyribose; 63231-63-0/RNA; EC 2.4.2.-/Pentosyltransferases; EC 2.4.2.29/queuine tRNA-ribosyltransferase
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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