Abnormal heme distribution in mutant yeast cells

JULIA ALEJANDRA CRICCO; COBINE, P.; WINGE, D.

Rosario

Congreso; XLII Reunión Anual SAIB Sociedad Argentina de Bioquímica y Biología Molecular.; 2006

SAIB

Abnormal heme distribution in mutant yeast cells  Julia A. Criccoa, Paul A. Cobineb, Dennis R. Wingeb a IBR CONICET-U.N.R. - Rosario - Argentina b Department of Biochemistry, University of Utah - U.S.A.     Heme is a critical cofactor required for many biological processes. In eukaryotic cells, the last steps of heme biosynthesis are carried out in the mitochondria, but how it is delivered to the target proteins still unknown. In Saccharomyces cerevisiae, deletion of the genes YLR201C and YOR205C results in respiratory deficient strains. Both are nuclear genes that encode mitochondrial proteins. Jonhnson et al. named the YLR201C gene product as Coq9, because this protein is involved in CoQ biosynthesis (JBC 2005, 280, 42627-35). In our hands, those mutant strains have shown lower total heme content compared to the WT. This lack of heme is not a result of a blockage in the heme biosynthetic pathway or as a result of loss of mitochondrial DNA. In ylr201c cells the heme deficiency was restricted to the mitochondria being the cytosolic levels comparable to the WT. The deficiency of CoQ could affect assembly and/or maintenance of complex III and its absence the cause of heme-depleted mitochondria. Preliminary results on yol205c mutant cells show similar phenotype that coq9 mutant, although, it is not involved in heme or CoQ biosynthesis. The absence of this protein evidences a general effect over different components of respiratory chain of yeast mitochondria.