J. Biochem, 1990, Vol. 107, No. 5 714-717
© 1990 Japanese Biochemical Society
research-article |
The Methanol-Oxidizing System of Methylobacterium extorquens AM1 Reconstituted with Purified Constituents
Department of Life Science, Faculty of Science, Tokyo Institute of Technology O-okayama, Meguro-ku, Tokyo 152
1To whom all correspondence should be addressed.
The electron transport system (with cytochrome a a3) coupled to the oxidation of methanol in Methylobacterium extorquens AM1 (former pseudomonas AM1) was reconstituted with highly purified constituents of the system. A mixture of 2.7 µM methanol dehydrogenase, 3.2 µM cytochrome CH, and 71 nM cytochrome c oxidase (=cytochrome aa3) consumed oxygen at a lower rate in the presence of methanol, while its activity was enhanced 3-fold by the addition of 1.4 µM cytochrome cL (74 mol of O2 consumed/mol of heme a of cytochrome c oxidase per min). Further addition of amicyanin to the above mixture did not affect the activity. Although ammonium ion greatly activated the activity of methanol dehydrogenase, the ion had little effect on the oxygen consumption activity of the above mixture. On the basis of the results obtained in the present study, an electron transport system is proposed for the oxidation of methanol in M. extorquens AM1.