Characterization of a Cryptic Gene Pair from Neisseria gonorrhoeae That Is Common to Pathogenic Neisseria Species

A pair of genes, each of which produces in Escherichia coli a 20-kDa, periplasmically localized protein that cross-reacts with anti-rpoN monoclonal antibody, was isolated from Neisseria gonorrhoeae. Homologs of the two genes were detected in pathogenic Neisseria species but not in commensal species. These genes are designated cnpl and cnp2 (cryptic neisserial protein). Many bacterial pathogens possess complex systems that regulate the transcription of virulence factors in response to changing environmental conditions (18). While several viru-lence factors have been identified in Neisseria gonorrhoeae (the outer membrane proteins PI, PII, and PIII; immuno-globulin A protease; lipo-oligosaccharide; and pili), no envi-ronmental regulation of these major virulence factor genes has been described. In contrast, two systems of global regulation, controlled by the availability of iron (11, 32) or oxygen (4, 13), are virulence associated. The gonococcal pilus is essential for virulence. A two