Document Detail


HlyU acts as an H-NS antirepressor in the regulation of the RTX toxin gene essential for the virulence of the human pathogen Vibrio vulnificus CMCP6.
MedLine Citation:
PMID:  19320834     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
In Vibrio vulnificus, HlyU upregulates the expression of the large RTX toxin gene. In this work we identified the binding site of HlyU to -417 to -376 bp of the rtxA1 operon transcription start site. lacZ fusions for a series of progressive deletions from the rtxA1 operon promoter showed that transcriptional activity increased independently of HlyU when its binding site was absent. Thus HlyU must regulate the rtxA1 operon expression by antagonizing a negative regulator. Concomitantly we found that an hns mutant resulted in an increase in the expression of the rtxA1 operon genes. Multiple copies of HlyU can increase the promoter activity only in the presence of H-NS underscoring the hypothesis that HlyU must alleviate the repression by this protein. H-NS binds to a region that extends upstream and downstream of the rtxA1 operon promoter. In the upstream region it binds to five AT-rich sites of which two overlap the HlyU binding site. Competitive footprinting and gel shift data demonstrate HlyU's higher affinity as compared with H-NS resulting in the de-repression and a corresponding increased expression of the rtxA1 operon.
Authors:
Moqing Liu; Hiroaki Naka; Jorge H Crosa
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2009-03-17
Journal Detail:
Title:  Molecular microbiology     Volume:  72     ISSN:  1365-2958     ISO Abbreviation:  Mol. Microbiol.     Publication Date:  2009 Apr 
Date Detail:
Created Date:  2009-04-30     Completed Date:  2009-05-21     Revised Date:  2011-01-10    
Medline Journal Info:
Nlm Unique ID:  8712028     Medline TA:  Mol Microbiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  491-505     Citation Subset:  IM    
Affiliation:
Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97239, USA.
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MeSH Terms
Descriptor/Qualifier:
Bacterial Proteins / genetics,  metabolism*
Bacterial Toxins / genetics,  metabolism*
Base Sequence
Binding Sites
DNA-Binding Proteins / genetics,  metabolism*
Gene Expression Regulation, Bacterial
Molecular Sequence Data
Operon
Promoter Regions, Genetic
Repressor Proteins / genetics,  metabolism*
Transcription Factors / genetics,  metabolism*
Transcription Initiation Site
Vibrio vulnificus / genetics*,  metabolism,  pathogenicity
Virulence
Grant Support
ID/Acronym/Agency:
AI065981/AI/NIAID NIH HHS; AI19018/AI/NIAID NIH HHS; R01 AI065981-03/AI/NIAID NIH HHS
Chemical
Reg. No./Substance:
0/Bacterial Proteins; 0/Bacterial Toxins; 0/DNA-Binding Proteins; 0/H-NS protein, bacteria; 0/Repressor Proteins; 0/RtxA protein, Vibrio cholerae; 0/Transcription Factors
Comments/Corrections

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