title: NMR structure of a type IVb pilin from Salmonella typhi and its assembly into pilus.
abstract: The structure of the N-terminal-truncated Type IVb structural pilin (t-PilS) from Salmonella typhi was determined by NMR. Although topologically similar to the recently determined x-ray structure of pilin from Vibrio cholerae toxin-coregulated pilus, the only Type IVb pilin with known structure, t-PilS contains many distinct structural features. The protein contains an extra pair of beta-strands in the N-terminal alphabeta loop that align with the major beta-strands to form a continuous 7-stranded antiparallel beta-sheet. The C-terminal disulfide-bonded region of t-PilS is only half the length of that of toxin-coregulated pilus pilin. A model of S. typhi pilus has been proposed and mutagenesis studies suggested that residues on both the alphabeta loop and the C-terminal disulfide-bonded region of PilS might be involved in binding specificity of the pilus. This model structure reveals an exposed surface between adjacent subunits of PilS that could be a potential binding site for the cystic fibrosis transmembrane conductance regulator.
authors.affiliation: Department of Biological Sciences, National University of Singapore, Singapore 117543.
authors.forename: Xing-Fu
authors.initials: XF
authors.lastname: Xu
authors.forename: Yih-Wan
authors.initials: YW
authors.lastname: Tan
authors.forename: Lam
authors.initials: L
authors.lastname: Lam
authors.forename: Jim
authors.initials: J
authors.lastname: Hackett
authors.forename: Mingjie
authors.initials: M
authors.lastname: Zhang
authors.forename: Yu-Keung
authors.initials: YK
authors.lastname: Mok
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D036781:Fimbriae Proteins / Q000737:chemistry* / Q000145:classification / Q000235:genetics; D010861:Fimbriae, Bacterial / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D012485:Salmonella typhi / Q000737:chemistry* / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity
chemical_list: D011994:Recombinant Proteins; D036781:Fimbriae Proteins