Identification of the exported proteins of the oral opportunistic pathogen Actinobacillus actinomycetemcomitans by using alkaline phosphatase fusions.

A phoA fusion library of Actinobacillus actinomycetemcomitans genomic DNA has been screened to identify genes encoding exported and secreted proteins. A total of 8,000 colonies were screened, and 80 positive colonies were detected. From these, 48 genes were identified with (i) more than half having homology to known or hypothetical Haemophilus influenzae genes, (ii) 14 having no ascribed function, and (iii) 4 having very limited or no homology to known genes. The proteins encoded by these genes may, by virtue of their presence on the cell surface, be novel virulence determinants.