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Characterization of S. cerevisiae Coq10p, a putative START domain Q‐binding protein
Author(s) -
Tsui Hui,
Clarke Catherine
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.568.27
Subject(s) - coenzyme q – cytochrome c reductase , saccharomyces cerevisiae , biochemistry , antimycin a , biology , mutant , inner mitochondrial membrane , biosynthesis , mitochondrion , mitochondrial respiratory chain , mitochondrial matrix , protein subunit , respiratory chain , yeast , cytochrome c , gene , cytosol , enzyme
Coenzyme Q (ubiquinone or Q) is an essential redox active lipid functioning in respiratory electron and proton transport in cellular energy metabolism and as an important lipid soluble antioxidant in cellular membranes. Nine COQ genes ( COQ1 – COQ9 ) have been identified in S. cerevisiae responsible for Q biosynthesis, and the encoded Coq polypeptides are organized in a multi‐subunit complex peripherally associated with the matrix side of the mitochondrial inner membrane. Coq10p, a recently discovered putative steroidogenic acute regulatory related lipid transfer (START) domain protein, is found to be required for Q function in respiratory electron transport and as an antioxidant. Unlike other Q‐less coq mutants, yeast coq10 mutants contain almost wild‐type steady‐state levels of Q 6 , although the rate of de novo Q biosynthesis in yeast cells during log phase growth is decreased. Treatment of coq10 mutant mitochondria with inhibitors of Complex III showed stimulated ROS formation in response to antimycin but not myxothiazol indicating an active Q‐cycle but a defect in transfer of electrons through cytochrome c . These observations suggest the Coq10 polypeptide is necessary for efficient Q biosynthesis and might function in delivery of Q to its proper site in complex III. Our tandem immuno‐ affinity‐purification scheme of tagged Coq10p has identified several potential protein binding partners of Coq10p in S. cerevisiae . We have also studied the lipid binding property of Coq10p after over‐expression and purification from E. coli . This research was supported by NSF MCB‐1330803.