Operation of the cbb₃-Type Terminal Oxidase in Azotobacter vinelandii

Yu. V. Bertsova and A. V. Bogachev^*

Department of Bioenergetics, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992 Russia; fax: (095) 939-0338; E-mail: sodiumc@genebee.msu.su

^* To whom correspondence should be addressed.

Received December 21, 2001; Revision received January 17, 2002

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A part of the gene encoding cbb₃-type cytochrome oxidase CcoN subunit was cloned from Azotobacter vinelandii and a mutant strain of this bacterium with disrupted ccoN gene was constructed. In contrast to the wild type strain, this one is unable to oxidize cytochromes c₄ and c₅. Thus, the A. vinelandii respiratory chain is shown to contain cbb₃-type cytochrome c oxidase. It is also shown that the activity of this enzyme is not necessary for diazotrophic growth of A. vinelandii at high oxygen concentrations.

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KEY WORDS: Azotobacter vinelandii, cytochrome oxidase, cbb₃-type cytochrome, respiratory protection

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