title: Diversity in the oligomeric channel structure of the multidrug efflux pumps in Pseudomonas aeruginosa.
abstract: MexAB-OprM, the multidrug efflux pump of Pseudomonas aeruginosa, contributes to the high resistance of this organism to a wide variety of antibiotics. To investigate the structure and function of OprM, the outer membrane channel of MexAB-OprM, we examined the oligomeric states of OprM and its homologues OprJ and OprN. These proteins were treated with crosslinking reagent after their reconstitution into liposome membranes. The crosslinked products indicated that OprM and OprN formed trimers, while OprJ unexpectedly appeared to form a tetramer. In order to test whether differences in oligomeric structure might be intimately related to channel function, we examined the channel-forming activity of these proteins by liposome swelling assay. However, no significant differences in channel characteristics were detected among OprM, OprJ, and OprN. We proposed the probable explanation for the diversity in the oligomeric structure of the channel proteins.
authors.affiliation: Department of Molecular Life Science, Tokai University School of Medicine, Kanagawa, Japan. eisaku@is.icc.u-tokai.ac.jp
authors.forename: Eisaku
authors.initials: E
authors.lastname: Yoshihara
authors.forename: Shima
authors.initials: S
authors.lastname: Eda
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000502:physiology; D015153:Blotting, Western; D003432:Cross-Linking Reagents; D024901:Drug Resistance, Multiple, Bacterial; D004591:Electrophoresis, Polyacrylamide Gel; D008081:Liposomes; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000502:physiology; D010539:Permeability; D021122:Protein Subunits / Q000032:analysis; D011550:Pseudomonas aeruginosa / Q000737:chemistry* / Q000187:drug effects*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D003432:Cross-Linking Reagents; D008081:Liposomes; D026901:Membrane Transport Proteins; C470190:OprJ protein, Pseudomonas aeruginosa; C402263:OprM protein, Pseudomonas aeruginosa; C105708:OprN protein, Pseudomonas aeruginosa; D021122:Protein Subunits