Identification of six major outer membrane proteins from Actinobacillus actinomycetemcomitans

Abstract We have identified six major sarcosyl-insoluble outer membrane proteins (Omp) of Actinobacillus actinomycetemcomitans Y4, and designated them as Omp100, Omp64, Omp39, Omp29, Omp18 and Omp16 according to the molecular mass. A similar N-terminal sequence was found in the first 15 amino acid residues of Omp16 and Omp18. The N-terminal sequence of Omp29 matched perfectly with the sequence previously identified. We cloned and determined the DNA sequences of three complete genes encoding Omp100 , Omp64 and Omp18 / 16 , and one incomplete gene encoding Omp39 . Each Omp revealed homologies with some bacterial virulence factors responsible for adhesion, invasion, serum resistance, or protein antigenicity. Serum from patients with periodontitis suspected to be related to A . actinomycetemcomintans infection strongly reacted with Omp100, Omp29 and Omp16 as did serum from mice immunized with A . actinomycetemcomitans Y4 whole bacteria. These findings suggest that Omps of A . actinomycetemcomitans can be associated with periodontal disease.