Role of histone-like proteins H-NS and StpA in expression of virulence determinants of uropathogenic Escherichia coli.
The histone-like protein H-NS is a global regulator in Escherichia coli that has been intensively studied in nonpathogenic strains. However, no comprehensive study on the role of H-NS and its paralogue, StpA, in gene expression in pathogenic E. coli has been carried out so far. Here, we monitored the global effects of H-NS and StpA in a uropathogenic E. coli isolate by using DNA arrays. Expression profiling revealed that more than 500 genes were affected by an hns mutation, whereas no effect of StpA alone was observed. An hns stpA double mutant showed a distinct gene expression pattern that differed in large part from that of the hns single mutant. This suggests a direct interaction between the two paralogues and the existence of distinct regulons of H-NS and an H-NS/StpA heteromeric complex. hns mutation resulted in increased expression of alpha-hemolysin, fimbriae, and iron uptake systems as well as genes involved in stress adaptation. Furthermore, several other putative virulence genes were found to be part of the H-NS regulon. Although the lack of H-NS, either alone or in combination with StpA, has a huge impact on gene expression in pathogenic E. coli strains, its effect on virulence is ambiguous. At a high infection dose, hns mutants trigger more sudden lethality due to their increased acute toxicity in murine urinary tract infection and sepsis models. At a lower infectious dose, however, mutants lacking H-NS are attenuated through their impaired growth rate, which can only partially be compensated for by the higher expression of numerous virulence factors.
Müller
Claudia M
CM
Institut für Molekulare Infektionsbiologie, Röntgenring 11, D-97070 Würzburg, Germany.
Dobrindt
Ulrich
U
Nagy
Gábor
G
Emödy
Levente
L
Uhlin
Bernt Eric
BE
Hacker
Jörg
J
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004926:Escherichia coli / Q000235:genetics* / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000502:physiology*; D005260:Female; D052776:Female Urogenital Diseases / Q000382:microbiology*; D015964:Gene Expression Regulation, Bacterial; D044404:Genomic Islands; D006801:Humans; D051379:Mice; D018832:Molecular Chaperones / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics
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; D037521:Virulence Factors