Linked Life Data

21530538

Source:http://linkedlifedata.com/resource/pubmed/id/21530538

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2011-5-30
pubmed:abstractText
Eubacterial leucyl/phenylalanyl tRNA protein transferase (L/F transferase) catalyzes the transfer of a leucine or a phenylalanine from an aminoacyl-tRNA to the N-terminus of a protein substrate. This N-terminal addition of an amino acid is analogous to that of peptide synthesis by ribosomes. A previously proposed catalytic mechanism for Escherichia coli L/F transferase identified the conserved aspartate 186 (D186) and glutamine 188 (Q188) as key catalytic residues. We have reassessed the role of D186 and Q188 by investigating the enzymatic reactions and kinetics of enzymes possessing mutations to these active-site residues. Additionally three other amino acids proposed to be involved in aminoacyl-tRNA substrate binding are investigated for comparison. By quantitatively measuring product formation using a quantitative matrix-assisted laser desorption/ionization time-of-flight mass spectrometry-based assay, our results clearly demonstrate that, despite significant reduction in enzymatic activity as a result of different point mutations introduced into the active site of L/F transferase, the formation of product is still observed upon extended incubations. Our kinetic data and existing X-ray crystal structures result in a proposal that the critical roles of D186 and Q188, like the other amino acids in the active site, are for substrate binding and orientation and do not directly participate in the chemistry of peptide bond formation. Overall, we propose that L/F transferase does not directly participate in the chemistry of peptide bond formation but catalyzes the reaction by binding and orientating the substrates for reaction in an analogous mechanism that has been described for ribosomes.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
1089-8638
pubmed:author
pubmed:copyrightInfo
Copyright © 2011 Elsevier Ltd. All rights reserved.
pubmed:issnType
Electronic
pubmed:day
17
pubmed:volume
409
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
617-29
pubmed:meshHeading
pubmed:year
2011
pubmed:articleTitle
An alternative mechanism for the catalysis of peptide bond formation by L/F transferase: substrate binding and orientation.
pubmed:affiliation
Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't