Characterization of the neisserial lipid-modified azurin bearing the H.8 epitope

The pathogenic Neisseria have multiple genes encoding proteins that bind monoclonal antibody (MAb) H.8. We previously reported the cloning and sequencing of a meningococcal gene (laz) encoding an H.8 MAb-binding protein with a consensus lipoprotein processing site, an N-terminal domain containing the epitope for H.8 MAb binding, and a C-terminal domain with extensive similarity to the sequences of azurins from other organisms. In the current study, we showed that the product of the cloned gene could be labelled with palmitic acid, that it was subject to globomycin-sensitive processing, and that it was immunologically cross-reactive with azurin from Pseudomonas aeruginosa. All neisserial species tested, both pathogens and commensals, produced a protein recognized by anti-azurin serum. Southern blots with oligonucleotide probes specific for the azurin domain of the gene showed that it was present in a single copy in the chromosome; it was highly conserved in gonococci and meningococci, and less conserved in commensal Neisseria species.