title: Expression of the hemolysin operon in Escherichia coli is modulated by a nucleoid-protein complex that includes the proteins Hha and H-NS.
abstract: The Escherichia coli protein Hha is a temperature- and osmolarity-dependent modulator of the expression of the hemolysin operon. The Hha protein was purified and its DNA-binding properties analyzed. Hha binds in a non-specific manner throughout the upstream regulatory region of the hemolysin operon in the recombinant hemolytic plasmid pANN202-312. A search for interacting proteins revealed that Hha interacts with H-NS. DNA-binding studies showed that, in vitro, Hha and H-NS together form a complex with DNA that differs from those formed with either protein alone. These data, together with the effects of hha and hns mutations on the expression of the hemolysin genes, suggest that in vivo H-NS and Hha form a nucleoid-protein complex that accounts for the thermo-osmotic regulation of the hemolysin operon in E. coli.
authors.affiliation: Departament de Microbiologia, Universitat de Barcelona, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: Nieto
authors.forename: C
authors.initials: C
authors.lastname: Madrid
authors.forename: A
authors.initials: A
authors.lastname: Prenafeta
authors.forename: E
authors.initials: E
authors.lastname: Miquelay
authors.forename: C
authors.initials: C
authors.lastname: Balsalobre
authors.forename: M
authors.initials: M
authors.lastname: Carrascal
authors.forename: A
authors.initials: A
authors.lastname: Juárez
mesh_terms: D001426:Bacterial Proteins / Q000302:isolation & purification / Q000378:metabolism*; D015153:Blotting, Western; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins / Q000235:genetics* / Q000378:metabolism; D008957:Models, Genetic; D009876:Operon; D009994:Osmolar Concentration; D010957:Plasmids; D011485:Protein Binding; D013696:Temperature; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C031908:H-NS protein, bacteria; D006460:Hemolysin Proteins; C079209:hha protein, E coli; D004247:DNA; D001616:beta-Galactosidase