Histidine 129 in the 75-kDa Subunit of Mitochondrial Complex I from Yarrowia lipolytica Is Not a Ligand for [Fe4S4] Cluster N5 but Is Required for Catalytic Activity*
- Antje Waletko,
- Klaus Zwicker,
- Albina Abdrakhmanova,
- Volker Zickermann,
- Ulrich Brandt and
- Stefan Kerscher‡
- Universität Frankfurt, Fachbereich Medizin, Institut für Biochemie I, F-60590 Frankfurt am Main, Germany
- ↵‡ To whom correspondence should be addressed. Tel.: 49-6301-6943; Fax: 49-6301-6970; E-mail: kerscher{at}zbc.kgu.de.
Abstract
Respiratory chain complex I contains 8–9 iron-sulfur clusters. In several cases, the assignment of these clusters to subunits and binding motifs is still ambiguous. To test the proposed ligation of the tetranuclear iron-sulfur cluster N5 of respiratory chain complex I, we replaced the conserved histidine 129 in the 75-kDa subunit from Yarrowia lipolytica with alanine. In the mutant strain, reduced amounts of fully assembled but destabilized complex I could be detected. Deamino-NADH: ubiquinone oxidoreductase activity was abolished completely by the mutation. However, EPR spectroscopic analysis of mutant complex I exhibited an unchanged cluster N5 signal, excluding histidine 129 as a cluster N5 ligand.
- Received October 8, 2004.
- Revision received November 24, 2004.
- The American Society for Biochemistry and Molecular Biology, Inc.
