OLIGOPEPTIDE PERMEASE IN BORRELIA-BURGDORFERI - PUTATIVE PEPTIDE-BINDING COMPONENTS ENCODED BY BOTH CHROMOSOMAL AND PLASMID LOCI

To elucidate the importance of oligopeptide permease for Borrelia burg dorferi, the agent of Lyme disease, a chromosomal locus in B. burgdorf eri that encodes homologues of all five subunits of oligopeptide perme ase has been identified and characterized. B. burgdorferi has multiple copies of the gene encoding the peptide-binding component, OppA; thre e reside at the chromosomal locus and two are on plasmids. Northern an alyses indicate that each oppA gene is independently transcribed, alth ough the three chromosomal oppA genes are also expressed as bi-and tri -cistronic messages. Induction of one of the plasmid-encoded oppA gene s was observed following an increase in temperature, which appears to be an important cue for adaptive responses in vivo. The deduced amino acid sequences suggest that all five borrelial OppA homologues are lip oproteins, but the protease-resistance of at least one of them in inta ct bacteria is inconsistent with outer-surface localization. Insertion al inactivation of a plasmid-encoded oppA gene demonstrates that it is not essential for growth in culture.