Journal of Biochemistry Advance Access published online on May 4, 2009
Journal of Biochemistry, doi:10.1093/jb/mvp067
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Biochemical and spectroscopic properties of cyanide-insensitive quinol oxidase from Gluconobacter oxydans

mura51Department of Biomedical Chemistry, Graduate School of Medicine, the University of Tokyo, Bunkyo-ku, Tokyo 113-0033; 2ATP System Project, ERATO, JST, Nagatsuta, Yokohama, 226-0026; 3Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi 753-8515; 4Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502; 5Kitasato Institute for Life Sciences and Graduate School of Infection Control Sciences, Kitasato University, Minato-ku, Tokyo 108-8641, Japan
*To whom correspondence addressed. Tel: +81-3-5841-8202, Fax: +81-3-5841-3444, E-mail: tmogi{at}m.u-tokyo.ac.jp (T. Mogi). Tel: +81-83-933-5858, Fax: +81-83-933-5859, E-mail: kazunobu{at}agr.yamaguchi-u.ac.jp (K. Matsushita)
Received February 18, 2009; Accepted April 9, 2009
| Abstract |
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Cyanide-insensitive quinol oxidase (CioAB), a relative of cytochrome bd, has no spectroscopic features of hemes b595 and d in the wild-type bacteria and is difficult to purify for detailed characterization. Here we studied enzymatic and spectroscopic properties of CioAB from the acetic acid bacterium Gluconobacter oxydans. G. oxydans CioAB showed the Km value for ubiquinol-1 comparable to that of Escherichia coli cytochrome bd but it was more resistant to KCN and quinone-analog inhibitors except piericidin A and LL-Z1272
. We obtained the spectroscopic evidence for the presence of hemes b595 and d. Heme b595 showed the
peak at 587 nm in the reduced state and a rhombic high-spin signal at g = 6.3 and 5.5 in the air-oxidized state. Heme d showed the
peak at 626 and 644 nm in the reduced and air-oxidized state, respectively, and an axial high-spin signal at g = 6.0 and low-spin signals at g = 2.63, 2.37 and 2.32. We found also a broad low-spin signal at g = 3.2, attributable to heme b558. Further, we identified the presence of heme D by mass spectrometry. In conclusion, CioAB binds all three heme species present in cytochrome bd quinol oxidase.
Key Words: Acetic acid bacteria, Cyanide-insensitive oxidase, Cytochrome bd, Heme d, Quinol oxidase
Present address: Department of Bioscience and Biotechnology, Faculty of Agriculture, University of the Ryukyus, Okinawa 903-0213, Japan