RESEARCH ARTICLE Mitochondrial fatty acid synthesis coordinates oxidative metabolism in mammalian mitochondria Sara M Nowinski1, Ashley Solmonson2, Scott F Rusin3, J Alan Maschek4,5,6, Claire L Bensard1, Sarah Fogarty1,7, Mi-Young Jeong1, Sandra Lettlova1, Jordan A Berg1, Jeffrey T Morgan1,7, Yeyun Ouyang1, Bradley C Naylor6, Joao A Paulo3, Katsuhiko Funai4, James E Cox1,4,6, Steven P Gygi3, Dennis R Winge1,4,8, Ralph J DeBerardinis2,7, Jared Rutter1,4,7* 1Department of Biochemistry, Salt Lake City, United States; 2Children’s Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, United States; 3Department of Cell Biology, Harvard University School of Medicine, Boston, United States; 4Diabetes & Metabolism Research Center, Salt Lake City, United States; 5Department of Nutrition and Integrative Physiology, Salt Lake City, United States; 6Metabolomics, Proteomics and Mass Spectrometry Core Research Facilities University of Utah, Salt Lake City, United States; 7Howard Hughes Medical Institute, Salt Lake City, United States; 8Department of Internal Medicine, Salt Lake City, United States Abstract Cells harbor two systems for fatty acid synthesis, one in the cytoplasm (catalyzed by fatty acid synthase, FASN) and one in the mitochondria (mtFAS). In contrast to FASN, mtFAS is poorly characterized, especially in higher eukaryotes, with the major product(s), metabolic roles, and cellular function(s) being essentially unknown. Here we show that hypomorphic mtFAS mutant mouse skeletal myoblast cell lines display a severe loss of electron transport chain (ETC) complexes and exhibit compensatory metabolic activities including reductive carboxylation. This effect on ETC *For correspondence: complexes appears to be independent of protein lipoylation, the best characterized function of
[email protected] mtFAS, as mutants lacking lipoylation have an intact ETC.