The gram negative bacterium Neisseria gonorrhoea is the causative agent of gonorrhea in man. Many basic questions concerning gonococcal pathogenicity remain unanswered due to the lack of an adequate animal model for this disease. The research outlined is designed to examine genetic mechanisms by which the gonococcus regulates the expression of a major surface structure, the pilus. Gonococcal pilin is a member of a family of pilins that share amino acid sequence homology. The pilin genes from N. gonorrhoea, Pseudomonas aeruginosa, Bacteroides nodous, and Moraxella bovis all show significant DNA sequence homology within their structural genes, and also show DNA sequence homology to the sigma factor binding sequence present in the 5' untranscribed regions of nitrogen fixation and nitrogen utilization genes. In E. coli, expression of a pilin beta-galactosidase fusion is stimulated 40- fold by expression of a cloned Klebsiella pneumonia nifA gene. Pilin expression has been found to be regulated by two gene products from pilA and pilB. The relationship between pilA and pilB regulation and the sigma factor binding site will be investigated utilizing gene fusions and site directed mutagenesis. The gene encoding the sigma factor will be isolated and the effect of mutations in this activity assayed. The possibility of a regulatory system related to nifA, but distinct from pilA and pilB will also be investigated.
