Document Detail

Plasticity in amino acid sensing of the chimeric receptor Taz.
MedLine Citation:
PMID:  16164563     Owner:  NLM     Status:  MEDLINE    
Taz is a chimeric receptor consisting of the periplasmic, transmembrane and most of the HAMP linker domains of the Escherichia coli aspartate receptor (Tar(Ec)) and the cytoplasmic signalling domain of the E. coli osmosensor EnvZ. Aspartate is one of several attractant ligands normally sensed by Tar and it interacts with Taz to induce OmpR-dependent transcription from the ompC promoter--albeit with reduced sensitivity relative to the chemotactic response it evokes via Tar. By combining Taz with a reporter system that expresses green fluorescent protein (GFP) from the ompC promoter, we were able to examine the interaction of Taz with all 20 natural amino acids. Some amino acids (Leu, Met, Val and Ser) reduced GFP expression, which in the case of leucine is likely attributed to a direct effect on the receptor, rather than an indirect effect through the leucine responsive protein (Lrp). Surprisingly, amino acids like Met and Ser--which are also attractants for Tar--'inhibited' Taz. Moreover, Taz exhibits a higher sensitivity to Leu compared with Asp, which is the inverse of Tar. Our results show the exquisite sensitivity of chemotactic receptors. Small conformational changes induced by making the chimera may have changed the way it responds to different amino acids.
Konstantinos M Michalodimitrakis; Victor Sourjik; Luis Serrano
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Molecular microbiology     Volume:  58     ISSN:  0950-382X     ISO Abbreviation:  Mol. Microbiol.     Publication Date:  2005 Oct 
Date Detail:
Created Date:  2005-09-16     Completed Date:  2006-04-13     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8712028     Medline TA:  Mol Microbiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  257-66     Citation Subset:  IM    
EMBL, Meyerhofstrasse 1, D-69117 Heidelberg, Germany.
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MeSH Terms
Amino Acids / metabolism*
Bacterial Outer Membrane Proteins / genetics,  metabolism*
Bacterial Proteins
Chemoreceptor Cells
Escherichia coli / metabolism,  physiology*
Escherichia coli Proteins / genetics,  metabolism*
Gene Expression Regulation, Bacterial
Genes, Reporter
Green Fluorescent Proteins / genetics
Leucine / metabolism
Multienzyme Complexes / genetics,  metabolism*
Receptors, Cell Surface / genetics,  metabolism*
Recombinant Fusion Proteins / genetics,  metabolism
Signal Transduction / genetics
Reg. No./Substance:
0/Amino Acids; 0/Bacterial Outer Membrane Proteins; 0/Bacterial Proteins; 0/Escherichia coli Proteins; 0/Multienzyme Complexes; 0/Receptors, Cell Surface; 0/Recombinant Fusion Proteins; 0/Tar protein, E coli; 147336-22-9/Green Fluorescent Proteins; 61-90-5/Leucine; EC 2.7.3.-/envZ protein, E coli

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

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