Characterisation of Campylobacter jejuni glycoprotease and its Role in Bacteria - Host Interactions

Abstract

The bacterial enzyme glycoprotease (gcp) was first discovered in the culture supernatant of Mannheimia (Pasteurella) haemolytica A1 associated with bovine pneumonic pasteurellosis. The enzyme is highly specific for O-sialoglycoproteins, but the function of the enzyme in bacterial homeostasis was not fully elucidated. The in silico analysis of C. jejuni genome strain NCTC11168 has revealed Cj1344c, a protein with predicted amino acid sequence showing 55% similarity to the M. haemolytica O-sialoglycoprotease. The C. jejuni Cj1344c homologue was present in all to-date sequenced strains of C. jejuni with higher than 97% amino acid identity and an orthologue of this enzyme was present in other Campylobacter species, with greater than 70% amino acid similarity. The glycoprotease was also present in the genomes of Campylobacter related species, such as Helicobacter and Wollinella with 65-70% similarity to C. jejuni Cj1344c. Comparative analysis also identified presence of orthologues in bacterial species such as Bacillus anthracis, Staphylococcus aureus and Haemophilus influenzae, with more than 49% amino acid similarity to the predicted Cj1344c amino acid sequence. In this study, the utilisation of gene mutagenesis approach demonstrated that a putative glycoprotease (Cj1344c) is required for C. jejuni survival and growth, as the inactivation of the gene by insertion of an antibiotic resistance gene cassette resulted in bacterial death. The gene products essential for bacterial growth in vitro and survival during infection constitute an initial set of protein targets for the development of antibacterial vaccines. The results of this study indicate that Cj1344c is a potential novel target for the development of antimicrobials against C. jejuni or a target for the development of a vaccine.