Dennis Winge
Professor of Medicine and of Biochemistry
B.A. Concordia College
Ph.D. Duke University
Research
Cytochrome oxidase (CcO) deficiency is of the most frequent causes of respiratory chain defects in humans. CcO is a 13 subunit complex functioning as the terminal electron acceptor in the mitochondrial respiratory chain that functions in oxidative phosphorylation (picture shown below). Known human mitochondrial myopathies presenting with CcO deficiencies represent mutations in six distinct CcO assembly factors that function in either the synthesis or insertion of essential cofactors for CcO. These assembly factors are conserved in eukaryotes and insights into their function were first gleaned from studies in yeast. The most common mutation leading to CcO deficiency and Leigh syndrome is the CcO assembly factor SURF1. We are focused on investigating the pathway of CcO biogenesis with the goal of understanding the pathway of assembly and the functional role of the myriad assembly factors. Our studies on the yeast ortholog of SURF1 support its dominant role in the insertion of the heme a cofactor. We seek to understand how mutations in human assembly factors compromise CcO assembly. We use a combination of in vitro biochemical, in vivo cellular assays and genetic analyses to elucidate the mechanism and pathway by which these assembly proteins mediate CcO formation.
A myriad of mitochondrial proteins like CcO require metal cofactors for biological function. We are interested in understanding how these mitochondrial metal ion pool are regulated so adequate pools exist for metallation reactions. We discovered a novel matrix copper complex that is used for the copper metallation of CcO and other mitochondrial cupro-enzymes. We are using biophysical techniques to structurally characterize the matrix copper complex and genetic approaches to identify the key transporters that transport copper ions into the matrix. An abundant metal ion in mitochondria is zinc. We discovered that mitochondria also contain a labile, storage pool of zinc that is utilized in metallation of key zinc metalloenzymes within the organelle. We are attempting to identify the labile zinc complex and proteins that regulate the bioavailable zinc pool that is used for zinc metallation reactions. Iron is a major nutrient in mitochondria and is used in formation of iron-sulfur clusters and heme. We are interested in the regulation of bioavailable iron pools within the organelle to permit iron-sulfur cluster and heme formation.
References
1. Rigby K, Cobine P, Khalimonchuk O, Winge D (2008) Mapping the interface of the Sco1:Cox2 interaction in cytochrome oxidase biogenesis. J. Biol. Chem. 283(22):15015-22
2. Kumanovics A, Chen O, Li L, Bagley D, Adkins E, Lin H, Dringra N, Outten C, Keller G, Winge D, Ward D, Kaplan J (2008) Identification of FRA1 and FRA2 as genes involved in regulating the yeast iron regulon in response to decreased mitochondrial iron-sulfur cluster synthesis. J. Biol. Chem. 283:10276-10286
3. Son M, Leary S, Romain N, Pierrel F, Winge D, Haller R, Elliott JL (2008) Isolated cytochrome c oxidase (COX) deficiency in G93A SOD1 mice over-expressing CCS protein. J. Biol. Chem. 283(18):12267-75
4. Pierrel F, Bestwick M, Cobine P, Khalimonchuk O, Cricco J, Winge D (2007) Coa1 links the Mss51 post-translational function to Cox1 cofactor insertion in cytochrome c oxidase assembly. EMBO Journal 26:4335-46
5. Khalimonchuk O, Bird A, Winge D (2007) Identification of a pro-oxidant intermediate in the assembly of cytochrome oxidase. J. Biol. Chem. 282:17442-17449
6. Leary SC, Winge DR (2007) The Janus face of copper: its expanding roles in biology and the pathophysiology of disease. EMBO Reports 8:224-227
7. Coyne HJ, Ciofi-Baffoni S, Banci L, Bertini I, Zhang L, George GN, Winge DR (2007) The characterization and role of zinc binding in yeast Cox4. J. Biol. Chem. 282:8926-8934
8. Rigby K, Zhang L, Cobine PA, George GN, Winge DR (2007) Characterization of the cytochrome c oxidase assembly factor Cox19 of Saccharomyces cerevisiae. J. Biol. Chem. 282:10233-10242
9. Leary SC, Cobine PA, Kaufman BA, Guercin G-H, Mattman A, Palaty J, Lockitch G, Winge DR, Rustin P, Horvath R, Shoubridge EA (2006) The human cytochrome c oxidase assembly proteins SCO1 and SCO2 are involved in the regulation of cellular copper homeostasis. Cell Metabolism 5:9-20
10. Bird AJ, Gordon M, Eide DJ, Winge DR (2006) Repression of ADH1 and ADH3 during zinc deficiency by Zap1-induced intergenic RNA transcripts. EMBO J. 25:5726-5734
11. Pierrel F, Cobine PA, Winge DR (2007) Metal ion availability in mitochondria. Biometals 20(3-4):675-82
12. Cobine PA, Pierrel F, Bestwick M, Winge DR (2006) Mitochondrial matrix copper complex used in metallation of cytochrome oxidase and superoxide dismutase. J Biol Chem 281:36552-36559
13. Cobine PA, Winge DR (2006) Visualizing the tri-coordinate copper intermediate in a copper transfer reaction. Nature Chemical Biology 2:352-353
14. Bird AJ, Swierczek S, Qiao W, Eide DJ, Winge DR (2006) Zinc metalloregulation of the zinc finger pair domain. J Biol Chem 281:25326-25335
15. Ojeda L, Keller G, Rutherford JC, Muhlenhoff U, Lill R, Winge DR (2006) Role of glutaredoxin-3 and glutaredoxin-4 in the iron-regulation of the Aft1 transcriptional activator in Saccharomyces cerevisiae. J Biol Chem 281:17661-17669
16. Yang M, Cobine PA, Molik S, Naranuntarat A, Lill R, Winge DR, Culotta VC (2006) The effects of mitochondrial iron homeostasis on cofactor specificity of superoxide dismutase 2. EMBO J 25:1775-83
17. Cobine PA, Pierrel F, Winge DR (2006) Copper trafficking to the mitochondrion and assembly of copper metalloenzymes. BBA-Molecular Cell Research 1763:759-772
