Transcriptional regulation of the esp genes of enterohemorrhagic Escherichia coli.
We have determined that the genes encoding the secreted proteins EspA, EspD, and EspB of enterohemorrhagic Escherichia coli (EHEC) are organized in a single operon. The esp operon is controlled by a promoter located 94 bp upstream from the ATG start codon of the espA gene. The promoter is activated in the early logarithmic growth phase, upon bacterial contact with eukaryotic cells and in response to Ca2+, Mn2+, and HEPES. Transcription of the esp operon seems to be switched off in tightly attached bacteria. The activation process is regulated by osmolarity (induction at high osmolarities), modulated by temperature, and influenced by the degree of DNA supercoiling. Transcription is sigmaS dependent, and the H-NS protein contributes to its fine tuning. Identification of the factors involved in activation of the esp operon and the signals responsible for modulation may facilitate understanding of the underlying molecular events leading to sequential expression of virulence factors during natural infections caused by EHEC.
Beltrametti
F
F
Department of Microbial Pathogenicity and Vaccine Research, Division of Microbiology, GBF-National Research Centre for Biotechnology, D-38124 Braunschweig, Germany.
Kresse
A U
AU
Guzmán
C A
CA
D000595:Amino Acid Sequence; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D001483:Base Sequence; D002118:Calcium / Q000494:pharmacology; D004278:DNA, Superhelical / Q000235:genetics / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology; D019453:Escherichia coli O157 / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial / Q000235:genetics; D006531:HEPES / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008345:Manganese / Q000494:pharmacology; D008969:Molecular Sequence Data; D009876:Operon / Q000235:genetics*; D009994:Osmolar Concentration; D011401:Promoter Regions, Genetic / Q000235:genetics; D012329:RNA, Bacterial / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D012808:Sigma Factor / Q000235:genetics / Q000502:physiology; D013696:Temperature; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics*
D001426:Bacterial Proteins; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C102051:EspA protein, E coli; C031908:H-NS protein, bacteria; D012329:RNA, Bacterial; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D008345:Manganese; D006531:HEPES; D002118:Calcium