MOMP (major outer membrane protein) of Campylobacter jejuni; a versatile pore-forming protein |
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Authors: | Dé E Jullien M Labesse G Pagès J M Molle G Bolla J M |
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Institution: | UMR 6522, CNRS, IFRMP 23, Faculté des Sciences, 76821, Mont-Saint-Aignan, France. |
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Abstract: | 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. |
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