The great majority of trimeric porins of Gram-negative bacteria cannot be dissociated into monomers without disrupting their folded conformation. The porin of Campylobacter jejuni, however, displays two folded structures, a classical oligomer and a monomer resistant to detergent denaturation. We probed the transition of trimer to monomer using light scattering experiments and examined the secondary structures of these two molecular states by infra-red spectroscopy. The channel-forming properties of both trimer and monomer were studied after incorporation into artificial lipid bilayers. In these conditions, the trimer induced ion channels with a conductance value of 1200 pS in 1 M NaCl. The pores showed marked cationic selectivity and sensitivity to low voltage. Analysis of the isolated monomer showed nearly the same single-channel conductance and the same selectivity and sensitivity to voltage. These results indicate that the folded monomer form of C. jejuni MOMP displays essentially the same pore-forming properties as the native trimer. Copyright (C) 2000 Federation of European Biochemical Societies.
Dé, E., Jullien, M., Labesse, G., Pagès, J. M., Molle, G., & Bolla, J. M. (2000). MOMP (major outer membrane protein) of Campylobacter jejuni; a versatile pore-forming protein. FEBS Letters, 469(1), 93–97. https://doi.org/10.1016/S0014-5793(00)01244-8