RT Journal Article SR Electronic(1) A1 Yoneyama, Hiroshi A1 Nakae, TaijiYR 1996 T1 Protein C (OprC) of the outer membrane of Pseudomonas aeruginosa is a copper-regulated channel protein JF Microbiology, VO 142 IS 8 SP 2137 OP 2144 DO https://doi.org/10.1099/13500872-142-8-2137 PB Microbiology Society, SN 1465-2080, AB Protein C (OprC) of the outer membrane of Pseudomonas aeruginosa forms small channels, as assayed by the liposome swelling method. We report here that OprC functions as a channel-forming and copper-binding protein. OprC purified to homogeneity formed a channel in planar lipid bilayers with an ion conductance of about 200 pS in 1 M NaCl. Cloning and sequencing of the gene encoding OprC revealed that it specified a polypeptide comprising 723 and 668 amino acid residues for the precursor and mature polypeptides (M r 73372), respectively. The amino acid sequence of OprC showed the highest degree of similarity with that of NosA of Pseudomonas stutzeri (65% sequence identity) which conveys Cu2+ to intracellular acceptor(s). OprC showed high copper-binding activity (K d = 2·6 μM) in aqueous solution containing surfactant. The expression of OprC appeared to be repressed by exogenous Cu2+ and derepressed by anaerobiosis in the presence of nitrate. These results suggest that OprC might be involved in copper utilization., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/13500872-142-8-2137