MOMP (major outer membrane protein) of Campylobacter jejuni; a versatile pore-forming protein.
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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UMR 6522, CNRS, IFRMP 23, Faculté des Sciences, 76821, Mont-Saint-Aignan, France.
Jullien
M
M
Labesse
G
G
Pagès
J M
JM
Molle
G
G
Bolla
J M
JM
D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry*; D016123:Campylobacter jejuni / Q000737:chemistry*; D004594:Electrophysiology; D008051:Lipid Bilayers / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry*; D018272:Porins / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D012542:Scattering, Radiation; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared
D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D008051:Lipid Bilayers; D008565:Membrane Proteins; D018272:Porins; D012967:Sodium Dodecyl Sulfate