CONFORMATIONAL-ANALYSIS OF THE CAMPYLOBACTER-JEJUNI PORIN

The major outer membrane protein (MOMP) of Campylobacter jejuni was pu rified to homogeneity by selective solubilization and fast protein liq uid chromatography. The amino acid composition of the MOMP indicates t he presence of cysteine residues. The amino-terminal sequence, determi ned over 31 residues, shows no significant homology with any other por in from gram-negative bacteria except in a discrete region. Immunocros s-reactivity between Escherichia coli OmpC and the MOMP aas analyzed, and a common antigenic site between these two porins was identified wi th an anti-peptide antibody. From circular dichroism and immunological investigations, the existence of a stable folded monomer, containing a high level of beta-sheet secondary structure, is evident. Conformati onal analyses show the presence of a native trimeric state generated b y association of the three folded monomers; the stability of this trim er is reduced compared with that of E. coli porins. This study clearly reveals that the C. jejuni MOMP is related to the family of trimeric bacterial porins.