title: Role of plasmid- and chromosomally encoded Hha proteins in modulation of gene expression in E. coli O157:H7.
abstract: H-NS and Hha belong to the nucleoid-associated family of proteins and modulate gene expression in response to environmental stimuli. Genes coding for these proteins can be either chromosomally or plasmid-encoded. In this work, we analyse the regulatory role of the Hha protein encoded in the virulence plasmid of the enterohemorrhagic Escherichia coli O157:H7 (Hha(pO157)). This plasmid is present in all clinical isolates of E. coli O157:H7 and contributes to virulence. Both, Hha(pO157) and E. coli O157:H7-chromosomal Hha (Hhachr) exhibit a significant degree of similarity. The hha gene from plasmid pO157 is transcribed from its own putative promoter and is overexpressed in a chromosomal hha mutant. As its chromosomal counterpart, Hha(pO157) is able to interact with H-NS. Remarkably, Hha(pO157) targets only a subset of the genes modulated by Hhachr. This has been evidenced by both assaying the ability of Hha(pO157) to complement expression of a specific operon (i.e., the haemolysin operon) and by comparing the global transcriptome of the wt strain and its hhap, hhac and hhapc mutant derivatives. Hha(pO157) and Hhachr share some common regulatory features, however they also display specific targeting of some genes and even a different modulatory role in some others.
authors: Departament de Microbiologia, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain. spaytubi@ub.edu
authors: Sonia
authors: S
authors: Paytubi
authors: Manuela
authors: M
authors: Dietrich
authors: Mário H
authors: MH
authors: Queiroz
authors: Antonio
authors: A
authors: Juárez
mesh_terms: D000595:Amino Acid Sequence; D002876:Chromosomes, Bacterial / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D019453:Escherichia coli O157 / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D036781:Fimbriae Proteins / Q000235:genetics* / Q000378:metabolism; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D006460:Hemolysin Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D009876:Operon; D010957:Plasmids / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment; D014158:Transcription, Genetic; D014774:Virulence
chemical_list: D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C529458:FimG protein, E coli; D006460:Hemolysin Proteins; C079209:hha protein, E coli; D036781:Fimbriae Proteins