Genetic and biochemical analysis of gonococcal IgA1 protease: cloning in Escherichia coli and construction of mutants of gonococci that fail to produce the activity.

Abstract

The biological significance of bacterial extracellular proteases that specifically cleave human IgA1 is unknown. A gene bank of gonococcal chromosomal DNA in E. coli K-12 was prepared using a cosmid cloning system. Among these clones, an E. coli strain that elaborates an extracellular endopeptidase that is indistinguishable from gonococcal IgA1 protease in its substrate specificity and action on human IgA1 was identified and characterized. Analysis of recombinant plasmids and examination of plasmid-specific peptides in minicells shows that the IgA1 protease activity in E. coli is associated with expression of a MW 40,000 peptide. IgA1 protease-deficient mutants of Neisseria gonorrhoeae were isolated by reintroduction of physically defined deletions of the cloned gene into the gonococcal chromosome by transformation.