title: HbiF regulates type 1 fimbriation independently of FimB and FimE.
abstract: Type 1 fimbriae have been suggested to play a role in the pathogenesis of extraintestinal Escherichia coli infection. Type 1 fimbriation in E. coli is phase variable and known to be dependent upon FimB and FimE, the two recombinases that invert the molecular switch fimS and control the expression of the downstream fim operon. Here we showed that HbiF, a novel site-specific recombinase, inverted fimS independently of FimB and FimE. HbiF-mediated fimS inversion appeared to be predominantly switching from "off" (termed OFF) to "on" (termed ON) orientation. This is different from the fimS inversion mediated by either FimB (bidirectional ON to OFF and OFF to ON) or FimE (unidirectional ON to OFF). Constitutive expression of the hbiF gene in E. coli resulted in a fimS-locked-ON phenotype, which resulted in the pathogenic E. coli K1 strain being incapable of inducing a high degree of bacteremia in neonatal rats. Discovery of HbiF-mediated OFF-to-ON fimS switching provides a new opportunity to develop a strategy for the prevention and therapy of extraintestinal E. coli infection including bacteremia and meningitis.
authors.affiliation: Division of Pediatric Infectious Diseases, Johns Hopkins University School of Medicine, 600 North Wolfe St., Park 256, Baltimore, MD 21287, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Xie
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Yao
authors.forename: Vitaliy
authors.initials: V
authors.lastname: Kolisnychenko
authors.forename: Ching-Hao
authors.initials: CH
authors.lastname: Teng
authors.forename: Kwang Sik
authors.initials: KS
authors.lastname: Kim
mesh_terms: D000818:Animals; D016470:Bacteremia / Q000382:microbiology; D004268:DNA-Binding Proteins / Q000502:physiology*; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology*; D004927:Escherichia coli Infections / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000502:physiology*; D005260:Female; D010861:Fimbriae, Bacterial / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D019426:Integrases / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D045522:Recombinases / Q000502:physiology*; D011995:Recombination, Genetic
chemical_list: D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C512599:HbiF protein, E coli; D045522:Recombinases; C081956:fimB protein, E coli; C081955:fimE protein, E coli; D019426:Integrases