Nearest neighbor analysis of outer membrane proteins of nontypeable Haemophilus influenzae

The arrangement of outer membrane proteins on the surface of nontypeable Haemophilus influenzae was investigated with cleavable and noncleavable bis-imidate cross-linking agents. Whole organisms were subjected to cross-linking agents, and oligomers of proteins were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, two-dimensional gel electrophoresis, and immunoblot assay, using monoclonal antibodies to outer membrane proteins. The major outer membrane protein (P2) formed dimers and trimers detected by all three methods. Oligomers of other outer membrane proteins were not detected. These data indicate that P2 exists as a trimer on the outer membrane and suggest that other outer membrane proteins exist as monomers on the outer membrane.