JlpA, a novel surface-exposed lipoprotein specific to Campylobacter jejuni, mediates adherence to host epithelial cells

A 1116 bp open reading frame (ORF), designated jlpA, encoding a novel speci es-specific lipoprotein of Campylobacter jejuni TGH9011, was identified fro m recombinant plasmid pHIP-O. The jlpA gene encodes a polypeptide (JlpA) of 372 amino acid residues with a molecular mass of 42.3 kDa. JlpA contains a typical signal peptide and lipoprotein processing site at the N-terminus. The presence of a lipid moiety on the JlpA molecule was confirmed by the in corporation of [H-3]-palmitic acid. Immunoblotting analysis of cell surface extracts prepared using glycine-acid buffer (pH 2.2) and proteinase K dige stion of whole cells indicated that JlpA is a surface-exposed lipoprotein i n C. jejuni. JlpA is loosely associated with the cell surface, as it is eas ily extracted from the C. jejuni outer membrane by detergents, such as sarc osyl and Triton X-100. JlpA is released to the culture medium, and its conc entration increases in a time-dependent fashion. The adherence of both inse rtion and deletion mutants of jlpA to HEp-2 epithelial cells was reduced co mpared with that of parental C. jejuni TGH9011. Adherence of C. jejuni to H Ep-2 cells was inhibited in a dose-dependent manner when the bacterium was preincubated with anti-GST-JlpA antibodies or when HEp-2 cells were preincu bated with JlpA protein. A ligand-binding immunoblotting assay showed that JlpA binds to HEp-2 cells, which suggests that JlpA is C. jejuni adhesin.