Mutation of the heme axial ligand of Escherichia coli succinate-quinone reductase: implications for heme ligation in mitochondrial complex II from yeast.

ABSTRACT: A b-type heme is conserved in membrane-bound complex II enzymes (SQR, succinate-ubiquinone reductase). The axial ligands for the low spin heme b in Escherichia coli complex II are SdhC His84 and SdhD His71. E. coli SdhD His71 is separated by 10 residues from SdhD Asp82 and Tyr83 which are essential for ubiquinone catalysis. The same His-10x-AspTyr motif dominates in homologous SdhD proteins, except for Saccharomyces cerevisiae where a tyrosine is at the axial position (Tyr-Cys-9x-AspTyr). Nevertheless, the yeast enzyme was suggested to contain a stoichiometric amount of heme, however, with the Cys ligand in the aforementioned motif acting as heme ligand. In this report, the role of Cys residues for heme coordination in the complex II family of enzymes is addressed. Cys was substituted to t

SUBMITTER: Maklashina E 

PROVIDER: S-EPMC2888824 | biostudies-literature | 2010 Jun-Jul

REPOSITORIES: biostudies-literature