title: Role of a putative third subunit YhcB on the assembly and function of cytochrome bd-type ubiquinol oxidase from Escherichia coli.
abstract: Recent proteome studies on the Escherichia coli membrane proteins suggested that YhcB is a putative third subunit of cytochrome bd-type ubiquinol oxidase (CydAB) (F. Stenberg, P. Chovanec, S.L. Maslen, C.V. Robinson, L.L. Ilag, G. von Heijne, D.O. Daley, Protein complexes of the Escherichia coli cell envelope. J. Biol. Chem. 280 (2005) 34409-34419). We isolated and characterized cytochrome bd from the DeltayhcB strain, and found that the formation of the CydAB heterodimer, the spectroscopic properties of bound hemes, and kinetic parameters for the ubiquinol-1 oxidation were identical to those of cytochrome bd from the wild-type strain. Anion-exchange chromatography and SDS-polyacrylamide gel electrophoresis showed that YhcB was not associated with the cytochrome bd complex. We concluded that YhcB is dispensable for the assembly and function of cytochrome bd. YhcB, which is distributed only in gamma-proteobacteria, may be a part of another membrane protein complex or may form a homo multimeric complex.
authors.affiliation: ATP System Project, ERATO, JST, Midori-ku, Yokohama, Japan. tmogi@res.titech.ac.jp
authors.forename: Tatsushi
authors.initials: T
authors.lastname: Mogi
authors.forename: Eri
authors.initials: E
authors.lastname: Mizuochi-Asai
authors.forename: Sachiko
authors.initials: S
authors.lastname: Endou
authors.forename: Satoru
authors.initials: S
authors.lastname: Akimoto
authors.forename: Hiro
authors.initials: H
authors.lastname: Nakamura
mesh_terms: D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000502:physiology*; D008970:Molecular Weight; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*; D017433:Protein Structure, Secondary
chemical_list: D029968:Escherichia coli Proteins; D010088:Oxidoreductases; C432586:ubiquinol oxidase; C506078:YhcB protein, E coli