title: Low cell density regulator AphA upregulates the expression of Vibrio vulnificus iscR gene encoding the Fe-S cluster regulator IscR.
abstract: IscR is a global transcriptional regulator that contributes to the pathogenesis of Vibrio vulnificus, a food-borne pathogen. In the present study, the regulatory mechanism for the iscR expression of V. vulnificus was evaluated. The expression of iscR was found to be upregulated by a transcriptional regulator AphA, a homologue of the low cell density regulator AphA of the Vibrio species, in the exponential phase of growth. The promoter activity of iscR appeared to be activated and repressed by AphA and IscR, respectively. EMSA and DNase I protection assay showed that both AphA and IscR bind to the iscR regulatory region and the binding site for AphA overlapped with part of the binding site for IscR. Further mutational analysis suggested that AphA upregulates the iscR expression only in the presence of functional IscR. An examination of the roles of AphA and the binding sites revealed that the binding of AphA would hinder the IscR-mediated repression of the iscR transcription. The combined results show that V. vulnificus AphA upregulates iscR expression by antagonizing its negative autoregulation.
authors.affiliation: National Research Laboratory of Molecular Microbiology and Toxicology, Department of Agricultural Biotechnology, Center for Food Safety and Toxicology, Seoul National University, Seoul, 151-921, Republic of Korea.
authors.forename: Jong Gyu
authors.initials: JG
authors.lastname: Lim
authors.forename: Jin Hwan
authors.initials: JH
authors.lastname: Park
authors.forename: Sang Ho
authors.initials: SH
authors.lastname: Choi
mesh_terms: D018983:DNA Footprinting; D004252:DNA Mutational Analysis; D004269:DNA, Bacterial / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D041261:Vibrio vulnificus / Q000235:genetics* / Q000254:growth & development
chemical_list: D004269:DNA, Bacterial; D014157:Transcription Factors