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Role of a putative third subunit YhcB on the assembly and function of cytochrome bd-type ubiquinol oxidase from Escherichia coli |
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| Authors: | Tatsushi Mogi Eri Mizuochi-Asai Satoru Akimoto |
| Affiliation: | a ATP System Project, ERATO, JST, Nagatsuta 5800-2, Midori-ku, Yokohama 226-0026, Japan b Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226-8503, Japan c Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan d RIKEN Harima Institute, Mikazuki-cho, Hyogo 679-5148, Japan e Graduate School of Integrated Science, Yokohama City University, Tsurumi, Yokohama, Kanagawa 230-0045, Japan |
| 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 ΔyhcB 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 γ-proteobacteria, may be a part of another membrane protein complex or may form a homo multimeric complex. |
| Keywords: | PAGE, polyacrylamide gel electrophoresis DS, dodecyl sucrose |
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