Primary structure analysis and adhesion studies on the major outer membrane protein of Campylobacter jejuni

The major outer membrane protein of Campylobacter jejuni (MOMP, 43 kDa), supposed to be one of the structures responsible for adhesion to INT 407 cells, was isolated from the crude outer membrane preparation by treatment with n-octyl-beta-D-glucopyranoside followed by preparative SDS-polyacrylamide gel electrophoresis. By cleavage of the isolated protein with cyanogen bromide and proteolytic enzymes, peptides were generated, separated by reverse phase high pressure liquid chromatography, and sequenced by automatic Edman degradation. The protein was aligned by identification of overlapping peptides. Treatment of bacteria with proteinase K prior to preparation of the outer membrane yielded a truncated MOMP with an apparent molecular mass of 25 kDa consisting of the C-terminal part of the protein. The isolated MOMP was functionally characterized by significant binding activity towards INT 407 cell membranes when isolated by preparative native gel electrophoresis, however, no binding activity was detected when the protein was isolated in the presence of SDS.