Cloning and characterization of an outer membrane protein (Lip18) from Helicobacter bizzozeronii

A recombinant lambda-Zap II phage was selected by screening a genomic library of Helicobacter bizzozeronii (Hb) using antibodies from a naturally infected cat. DNA sequencing resulted an open reading frame containing 172 codons with a predicted molecular mass of 18 kDa (Lip18). The amino acid sequence showed 22.1, 55.2, 56.7 and 57.1% identity to peptidoglycan-associated lipoprotein of Helicobacter pylori, Agrobacterium tumefaciens, Bartonella bacilliformis, respectively. A peptidoglycan associating alpha-helical motif (LALGQRRSVAVRDYLVS) was located in the C-terminal region. H. bizzozeronii contains a potential lipoprotein signal peptide cleavage site (Val-Val-Gly-Cys), and yields a predicted mature protein with 148 amino acids. The Lip18 was localized into the outer membrane of the bacteria. Immunoblot analysis of serum samples from a dog and cat naturally infected with Helicobacter spp was able to recognize the purified recombinant Lip18.