Restriction site polymorphism in genes encoding type 2 but not type 1 gonococcal IgA1 proteases.

Neisseria gonorrhoeae produces two phenotypically distinct types of IgA1 proteases, each of which cleaves a specific peptide bond in the hinge region of the human IgA1 heavy chain. The genes encoding IgA1 protease from twenty-eight different strains of N. gonorrhoeae, including twelve which produce type 1 enzyme, thirteen which produce type 2 enzyme, and three which are protease negative, were analyzed. Nine restriction site patterns were found in the iga genes. All twelve type 1 strains showed identical restriction maps of the iga gene, which differed from all the iga-2 variants. The three protease negative strains each contained DNA homologous to the probe. While strain to strain variation in restriction maps of specific genes is not unique and has been reported in N. gonorrhoeae previously, the existence of such restriction site polymorphism among iga-2 genes contrasts strongly with the lack of such variation among iga-1 genes. The basis for this lack of diversity among the iga-1 genes is under further investigation.