NADH oxidation by the Na+-translocating NADH: quinone oxidoreductase from Vibrio cholerae

NADH oxidation by the Na+-translocating NADH : quinone oxidoreductase from Vibrio cholerae

The Na(+)-translocating NADH:quinone oxidoreductase from Vibrio cholerae is a six subunit enzyme containing four flavins and a single motif for the binding of a Fe-S cluster on its NqrF subunit. This study reports the production of a soluble variant of NqrF (NqrF') and its individual flavin and Fe-S-carrying domains using V. cholerae or Escherichia coli as expression hosts. NqrF' and the flavin domain each contain 1 mol of FAD/mol of enzyme and exhibit high NADH oxidation activity (20,000 micromol min(-1) mg(-1)). EPR, visible absorption, and circular dichroism spectroscopy indicate that the Fe-S cluster in NqrF' and its Fe-S domain is related to 2Fe ferredoxins of the vertebrate-type. The addition of NADH to NqrF' results in the formation of a neutral flavosemiquinone and a partial reduction of the Fe-S cluster. The NqrF subunit harbors the active site of NADH oxidation and acts as a converter between the hydride donor NADH and subsequent one-electron reaction steps in the Na(+)-translocating NADH:quinone oxidoreductase complex. The observed electron transfer NADH --> FAD --> [2Fe-2S] in NqrF requires positioning of the FAD and the Fe-S cluster in close proximity in accordance with a structural model of the subunit.

Puhar, Andrea,1978-Mikrobiologisches Institut der Eidgenössischen Technischen Hochschule, ETH-Zentrum, CH-8092 Zürich, Switzerland(Swepub:umu)anpu0007 (author)
Neese, Frank (author)
Bill, Eckhard (author)
Fritz, Günter (author)
Steuber, Julia (author)
Mikrobiologisches Institut der Eidgenössischen Technischen Hochschule, ETH-Zentrum, CH-8092 Zürich, Switzerland (creator_code:org_t)

By the author/editor: Türk, Karin; Puhar, Andrea, 1 ...; Neese, Frank; Bill, Eckhard; Fritz, Günter; Steuber, Julia

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Biological Scien ...; and Microbiology

NATURAL SCIENCES: NATURAL SCIENCES; and Biological Scien ...; and Biochemistry and ...

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