Structure of the plant alternative oxidase: site-directed mutagenesis provides new information on the active site and membrane topology

Albury, Mary S, Affourtit, Charles, Crichton, Paul G and Moore, Anthony L (2002) Structure of the plant alternative oxidase: site-directed mutagenesis provides new information on the active site and membrane topology. Journal of Biological Chemistry, 277 (2). pp. 1190-1194. ISSN 0021-9258

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Abstract

All higher plants and many fungi contain an alternative oxidase (AOX), which branches from the cytochrome pathway at the level of the quinone pool. In an attempt, first, to distinguish between two proposed structural models of this di-iron protein, and, second, to examine the roles of two highly conserved tyrosine residues, we have expressed an array of site-specific mutants inSchizosaccharomyces pombe. Mitochondrial respiratory analysis reveals that S. pombe cells expressing AOX proteins in which Glu-217 or Glu-270 were mutated, no longer exhibit antimycin-resistant oxygen uptake, indicating that these residues are essential for AOX activity. Although such data corroborate a model that describes the AOX as an interfacial membrane protein, they are not in full agreement with the most recently proposed ligation sphere of its di-iron center. We furthermore show that upon mutation of Tyr-253 and Tyr-275 to phenylalanines, AOX activity is fully maintained or abolished, respectively. These data are discussed in reference to the importance of both residues in the catalytic cycle of the AOX.

Item Type: Article
Additional Information: On-going study on the alternative oxidase. ALM is PI who supervised the 2 postdocs on the project. First site-directed mutagenesis study on the active-site of the plant alternative oxidase to support current structure./Principal Investigator
Schools and Departments: School of Life Sciences > Biochemistry
Depositing User: Mary Albury
Date Deposited: 06 Feb 2012 20:07
Last Modified: 29 Jun 2012 09:17
URI: http://sro.sussex.ac.uk/id/eprint/24228
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