CuB promotes both binding and reduction of dioxygen at the heme-copper binuclear center in the Escherichia coli bo-type ubiquinol oxidase.
A CuB-deficient mutant of the Escherichia coli bo-type ubiquinol oxidase exhibits a very low oxidase activity that is consistent with a decreased dioxygen binding rate. During the turnover, a photolabile reaction intermediate persists for a few hundred milliseconds, due to much slower heme o-to-ligand electron transfer. Thus, the lack of CuB seems to have endowed the mutant enzyme with myoglobin-like properties, thereby stabilizing the CO-bound form, too. Accordingly we conclude that CuB plays a pivotal role in preferential trapping and efficient reduction of dioxygen at the heme-copper binuclear center.
Mogi
T
T
Department of Biological Sciences, Graduate School of Science, University of Tokyo, Japan.
Hirano
T
T
Nakamura
H
H
Anraku
Y
Y
Orii
Y
Y
D002248:Carbon Monoxide / Q000737:chemistry / Q000378:metabolism; D003300:Copper / Q000378:metabolism* / Q000502:physiology; D003576:Electron Transport Complex IV / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D006420:Hemeproteins / Q000378:metabolism*; D007700:Kinetics; D009154:Mutation; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D013057:Spectrum Analysis / Q000379:methods; D013997:Time Factors
D006420:Hemeproteins; D003300:Copper; D002248:Carbon Monoxide; C038862:cytochrome o oxidase; D003576:Electron Transport Complex IV; D010100:Oxygen