title: Differential effects and interactions of endogenous and horizontally acquired H-NS-like proteins in pathogenic Escherichia coli.
abstract: The nucleoid-associated protein H-NS is important for gene regulation in Escherichia coli. We have studied H-NS interaction with StpA and an uncharacterized H-NS-like protein, Hfp, in the uropathogenic E. coli isolate 536 that expresses all three nucleoid-associated proteins. We found distinct interactions of the three proteins at the protein level, resulting in the formation of heteromers, as well as differences in their gene expression at the transcriptional level. Mutants lacking either StpA or Hfp alone did not exhibit a phenotype at 37 degrees C, which is consistent with a low level of expression at that temperature. Expression of the hfp and stpA genes was found to be induced by apparently diametrical conditions, and StpA and Hfp levels could be correlated to modulatory effects on the expression of different H-NS targets, the bgl operon and operons for virulence factors such as fimbriae and capsular polysaccharide. The hns/hfp and hns/stpA double mutants displayed severe growth defects at low and high temperatures respectively. Our findings demonstrated different requirements for the alternative H-NS/Hfp/StpA combinations under these growth conditions. We propose that Hfp and StpA have distinct functions and roles in a dynamic pool of nucleoid-associated proteins that is adapting to requirements in a particular environment.
authors.affiliation: Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Umeå, Sweden.
authors.forename: Claudia M
authors.initials: CM
authors.lastname: Müller
authors.forename: György
authors.initials: G
authors.lastname: Schneider
authors.forename: Ulrich
authors.initials: U
authors.lastname: Dobrindt
authors.forename: Levente
authors.initials: L
authors.lastname: Emödy
authors.forename: Jörg
authors.initials: J
authors.lastname: Hacker
authors.forename: Bernt Eric
authors.initials: BE
authors.lastname: Uhlin
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D002876:Chromosomes, Bacterial / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D004777:Environment; D004926:Escherichia coli / Q000235:genetics* / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D036781:Fimbriae Proteins / Q000235:genetics; D010861:Fimbriae, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D007422:Intestines / Q000382:microbiology; D007700:Kinetics; D018832:Molecular Chaperones / Q000235:genetics; D008969:Molecular Sequence Data; D009876:Operon; D012097:Repressor Proteins / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C031908:H-NS protein, bacteria; D018832:Molecular Chaperones; D012097:Repressor Proteins; C090104:StpA protein, E coli; D036781:Fimbriae Proteins