title: Salmonella enterica serovar typhi uses type IVB pili to enter human intestinal epithelial cells.
abstract: DNA sequencing upstream of the Salmonella enterica serovar Typhi pilV and rci genes previously identified in the ca. 118-kb major pathogenicity island (X.-L. Zhang, C. Morris, and J. Hackett, Gene 202:139-146, 1997) identified a further 10 pil genes apparently forming a pil operon. The product of the pilS gene, prePilS protein (a putative type IVB structural prepilin) was purified, and an anti-prePilS antiserum was raised in mice. Mutants of serovar Typhi either lacking the whole pil operon or with an insertion mutation in the pilS gene were constructed, as was a strain in which the pilN to pilV genes were driven by the tac promoter. The pil(+) strains synthesized type IVB pili, as judged by (i) visualization in the electron microscope of thin pili in culture supernatants of one such strain and (ii) the presence of PilS protein (smaller than the prePilS protein by removal of the leader peptide) on immunoblotting of material pelleted by high-speed centrifugation of either the culture supernatant or sonicates of pil(+) strains. Control pil mutants did not express the PilS protein. A pilS mutant of serovar Typhi entered human intestinal INT407 cells in culture to levels only 5 to 25% of those of the wild-type strain, and serovar Typhi entry was strongly inhibited by soluble prePilS protein (50% inhibition of entry at 1.4 microM prePilS).
authors.affiliation: Department of Biochemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China.
authors.forename: X L
authors.initials: XL
authors.lastname: Zhang
authors.forename: I S
authors.initials: IS
authors.lastname: Tsui
authors.forename: C M
authors.initials: CM
authors.lastname: Yip
authors.forename: A W
authors.initials: AW
authors.lastname: Fung
authors.forename: D K
authors.initials: DK
authors.lastname: Wong
authors.forename: X
authors.initials: X
authors.lastname: Dai
authors.forename: Y
authors.initials: Y
authors.lastname: Yang
authors.forename: J
authors.initials: J
authors.lastname: Hackett
authors.forename: C
authors.initials: C
authors.lastname: Morris
mesh_terms: D000595:Amino Acid Sequence; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics*; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000382:microbiology*; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000235:genetics* / Q000648:ultrastructure; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology*; D008565:Membrane Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D009876:Operon; D011498:Protein Precursors / Q000235:genetics; D012485:Salmonella typhi / Q000235:genetics / Q000472:pathogenicity*; D017386:Sequence Homology, Amino Acid; D012703:Serotyping; D014157:Transcription Factors / Q000235:genetics; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; C077573:PilV protein, Bacteria; D011498:Protein Precursors; D014157:Transcription Factors; C080687:pilS protein, Bacteria; D036781:Fimbriae Proteins