Despite the fundamental roles of the mitochondrial respiratory chain (MRC) in both cellular energy production and a number of cardiovascular, neurodegenerative and inherited metabolic disorders, many factors required for MRC formation are currently unknown. In fact, almost 20% of the approximately 1000 known human mitochondrial proteins remain completely uncharacterized. Here we propose to address the gap in our understanding of MRC formation by systematically identifying and characterizing novel MRC biogenesis factors. We have developed an integrative genomic strategy based on clues from evolutionary history, high- throughput gene expression and protein interaction studies to discover novel MRC genes. Experimental work on two of our prioritized genes, C1orf31 and C6orf57, has shown their requirement for MRC complex IV and II biogenesis, respectively. Remarkably, a recent sequencing study identified mutations in C1orf31 in a mitochondrial disease patient. Due to the immediate relevance of C1orf31 to human health, we focused on characterizing the function of this protein in a yeast model where we demonstrated that copper supplementation rescued mitochondrial respiratory defects. In the current proposal we aim to: (1) Determine the role of C1orf31 in MRC complex IV assembly; (2) Investigate the pathological consequences of the loss of C1orf31 at the mitochondrial, cellular, and organismal level and determine the pathogenicity of patient mutations; and (3) Identify additional MRC biogenesis factors using our novel RNAi-based ?nutrient-sensitized? assay that utilizes differential growth of respiratory deficient human cells in glucose or galactose to interrogate mitochondrial respiration. We will perform in vitro biochemical experiments on purified C1orf31 and in vivo yeast genetic experiments to define the precise function of C1orf31 in MRC complex IV assembly. We will exploit our C1orf31 knockdown models in human cell lines and zebrafish embryos to simultaneously unravel the pathological consequences of lack of C1orf31 in mitochondrial, cellular, and organismal physiology, as well as test the hypothesis that these defects could be cured by copper supplementation. Finally, we will experimentally test our computationally predicted MRC biogenesis gene candidates, including C6orf57, for their role in cellular respiration using our nutrient-sensitized assay and assign hits to specific steps in the MRC biogenesis pathway. Thus, the impact of our work is both fundamental (elucidating basic mechanisms of MRC formation) and medical (providing the basis for molecular diagnosis of orphan mitochondrial disorders and a possible therapeutic option for patients with C1orf31 mutations).

Public Health Relevance

Despite the high prevalence of mitochondrial diseases, many of the proteins required for mitochondrial respiratory chain formation remain unknown. We have prioritized candidate genes required for formation of the mitochondrial respiratory chain, and mutations in one of the candidates were recently reported in a mitochondrial disease patient. Using yeast, human cells and zebrafish models we will define the role of the newly identified disease gene and other prioritized candidates in mitochondrial function to facilitate rapid diagnosis and therapeutic options for mitochondrial disease patients.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
3R01GM111672-06S1
Application #
10044168
Study Section
Program Officer
Anderson, Vernon
Project Start
2014-08-01
Project End
2023-08-31
Budget Start
2019-09-01
Budget End
2020-08-31
Support Year
6
Fiscal Year
2020
Total Cost
Indirect Cost
Name
Texas A&M Agrilife Research
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
847205713
City
College Station
State
TX
Country
United States
Zip Code
77845
Soma, Shivatheja; Latimer, Andrew J; Chun, Haarin et al. (2018) Elesclomol restores mitochondrial function in genetic models of copper deficiency. Proc Natl Acad Sci U S A 115:8161-8166
Basu Ball, Writoban; Baker, Charli D; Neff, John K et al. (2018) Ethanolamine ameliorates mitochondrial dysfunction in cardiolipin-deficient yeast cells. J Biol Chem 293:10870-10883
Basu Ball, Writoban; Neff, John K; Gohil, Vishal M (2018) The role of nonbilayer phospholipids in mitochondrial structure and function. FEBS Lett 592:1273-1290
Ghosh, Alok; Pratt, Anthony T; Soma, Shivatheja et al. (2016) Mitochondrial disease genes COA6, COX6B and SCO2 have overlapping roles in COX2 biogenesis. Hum Mol Genet 25:660-71
Baker, Charli D; Basu Ball, Writoban; Pryce, Erin N et al. (2016) Specific requirements of nonbilayer phospholipids in mitochondrial respiratory chain function and formation. Mol Biol Cell 27:2161-71
Tomar, Dhanendra; Dong, Zhiwei; Shanmughapriya, Santhanam et al. (2016) MCUR1 Is a Scaffold Factor for the MCU Complex Function and Promotes Mitochondrial Bioenergetics. Cell Rep 15:1673-85
Jayasundara, Nishad; Kozal, Jordan S; Arnold, Mariah C et al. (2015) High-Throughput Tissue Bioenergetics Analysis Reveals Identical Metabolic Allometric Scaling for Teleost Hearts and Whole Organisms. PLoS One 10:e0137710