Document Detail


Growth-phase-dependent expression of the operon coding for the glycosylated autotransporter adhesin AIDA-I of pathogenic Escherichia coli.
MedLine Citation:
PMID:  20831592     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The adhesin involved in diffuse adherence (AIDA-I) is an autotransporter found in pathogenic strains of Escherichia coli causing diarrhea in humans and pigs. The AIDA-I protein is glycosylated by a specific enzyme, the AIDA-associated heptosyltransferase (Aah). The aah gene is immediately upstream of the aidA gene, suggesting that they form an operon. However, the mechanisms of regulation of the aah and aidA genes are unknown. Using a clinical E. coli isolate expressing AIDA-I, we identified two putative promoters 149 and 128 nucleotides upstream of aah. Using qRT-PCR, we observed that aah and aidA are transcribed in a growth-dependent fashion, mainly at the start of the stationary phase. Western blotting confirmed that protein expression follows the same pattern. Using a fusion to a reporter gene, we observed that the regulation of the isolated aah promoter matched this transcription and expression pattern. Lastly, we found glucose to be a repressor and nutrient starvation to be an inducer. Taken together, our results suggest that, in the strain and the conditions we studied, aah-aidA is transcribed as a bicistronic message from a promoter upstream of aah, with maximal expression under conditions of nutrient limitation such as high cell density.
Authors:
Frédéric Berthiaume; Marie-Florence Leblond; Josée Harel; Michael Mourez
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-09-10
Journal Detail:
Title:  FEMS microbiology letters     Volume:  311     ISSN:  1574-6968     ISO Abbreviation:  FEMS Microbiol. Lett.     Publication Date:  2010 Oct 
Date Detail:
Created Date:  2010-09-23     Completed Date:  2011-01-05     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7705721     Medline TA:  FEMS Microbiol Lett     Country:  England    
Other Details:
Languages:  eng     Pagination:  176-84     Citation Subset:  IM    
Copyright Information:
© 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
Affiliation:
Department of Bacterial Animal Diseases, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada.
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MeSH Terms
Descriptor/Qualifier:
Adhesins, Escherichia coli / genetics*,  metabolism
Base Sequence
Escherichia coli / genetics,  growth & development*,  metabolism,  pathogenicity
Escherichia coli Infections / microbiology
Escherichia coli Proteins / genetics,  metabolism
Gene Expression Regulation, Bacterial*
Glycosylation
Glycosyltransferases / genetics,  metabolism
Humans
Molecular Sequence Data
Operon*
Promoter Regions, Genetic
Grant Support
ID/Acronym/Agency:
84578//Canadian Institutes of Health Research
Chemical
Reg. No./Substance:
0/AIDA-I protein, E coli; 0/Adhesins, Escherichia coli; 0/Escherichia coli Proteins; EC 2.4.-/Glycosyltransferases; EC 2.4.99.-/autotransporter-adhesin-heptosyltransferase, E coli

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