NMR structural studies on the pilin monomer pils from Salmonella typhi

Abstract

PilS is a type IVb pilin that assembles to form the pili of Salmonella typhi. The pilus is believed to be a major adhesin for the entry of this pathogen into intestinal epithelial cells via binding to CFTR. N-terminal truncated form of PilS was expressed, purified and studied by NMR. Near complete backbone and side chain resonance assignments were obtained using 15N and 13C labeled sample. Protein structure determined using NOE, hydrogen bond and dihedral angle restraints suggested that PilS adopted an I?/I? pilin fold containing 4 I?-helices packed against an anti-parallel I?-sheet formed by 7 I?-strands. The solution structure of pils is similar to the recently determined crystal structure of TCP pilin but with substantial differences.