title: Iron regulates expression of Bacillus cereus hemolysin II via global regulator Fur.
abstract: The capacity of pathogens to respond to environmental signals, such as iron concentration, is key to bacterial survival and establishment of a successful infection. Bacillus cereus is a widely distributed bacterium with distinct pathogenic properties. Hemolysin II (HlyII) is one of its pore-forming cytotoxins and has been shown to be involved in bacterial pathogenicity in a number of cell and animal models. Unlike many other B. cereus pathogenicity factors, HlyII is not regulated by pleiotropic transcriptional regulator PlcR but is controlled by its own regulator, HlyIIR. Using a combination of in vivo and in vitro techniques, we show that hlyII expression is also negatively regulated by iron by the global regulator Fur via direct interaction with the hlyII promoter. DNase I footprinting and in vitro transcription experiments indicate that Fur prevents RNA polymerase binding to the hlyII promoter. HlyII expression profiles demonstrate that both HlyIIR and Fur regulate HlyII expression in a concerted fashion, with the effect of Fur being maximal in the early stages of bacterial growth. In sum, these results show that Fur serves as a transcriptional repressor for hlyII expression.
authors.affiliation: Laboratory of Molecular Microbiology, Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Region, Russia. esineva@gmail.com
authors.forename: Elena
authors.initials: E
authors.lastname: Sineva
authors.forename: Andrey
authors.initials: A
authors.lastname: Shadrin
authors.forename: Ekaterina A
authors.initials: EA
authors.lastname: Rodikova
authors.forename: Zhanna I
authors.initials: ZI
authors.lastname: Andreeva-Kovalevskaya
authors.forename: Alexey S
authors.initials: AS
authors.lastname: Protsenko
authors.forename: Sergey G
authors.initials: SG
authors.lastname: Mayorov
authors.forename: Darya Yu
authors.initials: DY
authors.lastname: Galaktionova
authors.forename: Erica
authors.initials: E
authors.lastname: Magelky
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Solonin
mesh_terms: D001409:Bacillus cereus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006460:Hemolysin Proteins / Q000235:genetics / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000502:physiology; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C085361:ApxII toxin, bacteria; D001426:Bacterial Proteins; D006460:Hemolysin Proteins; D012097:Repressor Proteins; C068477:ferric uptake regulating proteins, bacterial; D007501:Iron; D012321:DNA-Directed RNA Polymerases