Characterization of outer membrane proteins from Actinobacillus actinomycetemcomitans

Outer membranes were prepared from whole cells of various strains of Actinobacillus actinomycetemcomitans and analysed by SDS-polyacrylamide gel (12.5%) electrophoresis (SDS-PAGE). In all strains four common major outer membrane proteins (OMPs) with molecular masses of 30, 34, 36 and 39 kDa could be distinguished. Heating the OMP preparation of strain Y4 at 60, 70, 90 and 100 degrees C produced a band of 30 kDa, which gradually lost its intensity from 70 degrees C onwards concomitantly with the development of two new protein bands of 34 and 36 kDa. Furthermore, the 36 kDa OMP appeared susceptible to proteolysis by trypsin; degraded products apparently produced a new electrophoretic band of 27 kDa. Y4-derived OMP fractions were solubilized with a Triton-SDS mixture to investigate the presence of peptidoglycan-associated proteins. The 39 kDa OMP was found to be peptidoglycan-associated.