| Collaborative regulation of Escherichia coli glutamate-dependent acid resistance by two AraC-like regulators, GadX and GadW (YhiW). | |
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MedLine Citation:
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PMID: 12446650 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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An important feature of Escherichia coli pathogenesis is an ability to withstand extremely acidic environments of pH 2 or lower. This acid resistance property contributes to the low infectious dose of pathogenic E. coli species. One very efficient E. coli acid resistance system encompasses two isoforms of glutamate decarboxylase (gadA and gadB) and a putative glutamate:gamma-amino butyric acid (GABA) antiporter (gadC). The system is subject to complex controls that vary with growth media, growth phase, and growth pH. Previous work has revealed that the system is controlled by two sigma factors, two negative regulators (cyclic AMP receptor protein [CRP] and H-NS), and an AraC-like regulator called GadX. Earlier evidence suggested that the GadX protein acts both as a positive and negative regulator of the gadA and gadBC genes depending on environmental conditions. New data clarify this finding, revealing a collaborative regulation between GadX and another AraC-like regulator called GadW (previously YhiW). GadX and GadW are DNA binding proteins that form homodimers in vivo and are 42% homologous to each other. GadX activates expression of gadA and gadBC at any pH, while GadW inhibits GadX-dependent activation. Regulation of gadA and gadBC by either regulator requires an upstream, 20-bp GAD box sequence. Northern blot analysis further indicates that GadW represses expression of gadX. The results suggest a control circuit whereby GadW interacts with both the gadA and gadX promoters. GadW clearly represses gadX and, in situations where GadX is missing, activates gadA and gadBC. GadX, however, activates only gadA and gadBC expression. CRP also represses gadX expression. It does this primarily by repressing production of sigma S, the sigma factor responsible for gadX expression. In fact, the acid induction of gadA and gadBC observed when rich-medium cultures enter stationary phase corresponds to the acid induction of sigma S production. These complex control circuits impose tight rein over expression of the gadA and gadBC system yet provide flexibility for inducing acid resistance under many conditions that presage acid stress. |
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Authors:
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Zhuo Ma; Hope Richard; Don L Tucker; Tyrrell Conway; John W Foster |
Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Journal of bacteriology Volume: 184 ISSN: 0021-9193 ISO Abbreviation: J. Bacteriol. Publication Date: 2002 Dec |
Date Detail:
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Created Date: 2002-11-26 Completed Date: 2002-12-19 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 2985120R Medline TA: J Bacteriol Country: United States |
Other Details:
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Languages: eng Pagination: 7001-12 Citation Subset: IM |
Affiliation:
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Department of Microbiology and Immunology, University of South Alabama College of Medicine, Mobile 36688, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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AraC Transcription Factor
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chemistry,
genetics,
physiology* Bacterial Proteins / biosynthesis, physiology Cyclic AMP Receptor Protein / physiology DNA-Binding Proteins / physiology Dimerization Escherichia coli / genetics, metabolism* Escherichia coli Proteins / chemistry, genetics, physiology* Genes, Regulator Glutamate Decarboxylase / genetics Glutamic Acid / metabolism* Hydrogen-Ion Concentration Membrane Proteins / genetics Promoter Regions, Genetic Repressor Proteins / physiology* Sigma Factor / biosynthesis Transcription, Genetic |
| Grant Support | |
ID/Acronym/Agency:
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R01-GM61147/GM/NIGMS NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/AraC Transcription Factor; 0/Bacterial Proteins; 0/Cyclic AMP Receptor Protein; 0/DNA-Binding Proteins; 0/Escherichia coli Proteins; 0/GadX protein, E coli; 0/H-NS protein, bacteria; 0/Membrane Proteins; 0/Repressor Proteins; 0/Sigma Factor; 0/sigma factor KatF protein, Bacteria; 56-86-0/Glutamic Acid; EC 4.1.1.-/gadA protein, E coli; EC 4.1.1.15/Glutamate Decarboxylase |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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