A vital characteristic of living systems is their ability to produce biological energy (ATP) efficiently. ATP is essential for cellular functions including biosynthesis, transport, signal transduction, chemo- and photo- taxis and thermogenesis. Energy producing complexes are widespread among organisms, and their improper function leads to devastating health problems and human diseases as well as low crop yields in plants. The long-term goal of this project is to understand the structure, mechanism of function and biogenesis of cytochrome (cyt) components of energy transduction pathways. These are important enzymes whose absence, or malfunction are the causes of multiple human diseases, including many muscular and neurological disorders. For these studies, prokaryotes provide simpler model systems that are evolutionarily conserved and closely related to eukaryotic organelles. This project uses molecular genetics, biochemical and biophysical approaches, with a sharp focus on the structure and function of the cyt bc1 or Complex III.
The specific aims of this proposal include 1- the molecular basis of oxygen tolerance of the quinol oxidation site of the cyt bc1 to address how this aerobic enzyme avoids the production of unwanted reactive oxygen species in the presence of oxygen, 2- exploration of the Zn binding residues of cyt b at the Qo site to probe their involvement in H+ conduction, and 3- development and characterization of heterodimer cyt bc1 variants to address intra- and inter-monomer structural and functional communications and regulations within the cyt bc1, to probe the links between the dimeric architecture and the mechanism of function of this enzyme. These studies are expected to greatly enhance our understanding and knowledge of energy transduction enzymes. Information gained using the simpler bacterial system could be generally applicable to the structurally more complex but functionally similar and evolutionarily related organelle-derived enzyme, and could provide invaluable information for elucidating the molecular bases and diagnoses of mitochondrial and other human diseases, including neuropathies, myopathies and aging.

Public Health Relevance

This research aims to define the structure-function and biogenesis of energy transduction enzymes. These proteins are the major sources of reactive oxygen species that are extremely harmful for human cells, and their biogenesis components form the molecular bases of many common mitochondrial diseases in humans. Malfunction of these enzymes induce multiple human illnesses, extending from maternally inherited mitochondrial diseases to neuromuscular degenerative disorders, as well as cancer and aging.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Macromolecular Structure and Function A Study Section (MSFA)
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Anderson, Vernon
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University of Pennsylvania
Schools of Arts and Sciences
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Verissimo, Andreia F; Daldal, Fevzi (2014) Cytochrome c biogenesis System I: an intricate process catalyzed by a maturase supercomplex? Biochim Biophys Acta 1837:989-98
Lanciano, Pascal; Khalfaoui-Hassani, Bahia; Selamoglu, Nur et al. (2013) Molecular mechanisms of superoxide production by complex III: a bacterial versus human mitochondrial comparative case study. Biochim Biophys Acta 1827:1332-9
Khalfaoui-Hassani, Bahia; Lanciano, Pascal; Lee, Dong-Woo et al. (2012) Recent advances in cytochrome bc(1): inter monomer electronic communication? FEBS Lett 586:617-21
Ekici, Seda; Pawlik, Grzegorz; Lohmeyer, Eva et al. (2012) Biogenesis of cbb(3)-type cytochrome c oxidase in Rhodobacter capsulatus. Biochim Biophys Acta 1817:898-910
Lanciano, Pascal; Lee, Dong-Woo; Yang, Honghui et al. (2011) Intermonomer electron transfer between the low-potential b hemes of cytochrome bc?. Biochemistry 50:1651-63
Guan, Ziqiang; Johnston, Norah C; Aygun-Sunar, Semra et al. (2011) Structural characterization of the polar lipids of Clostridium novyi NT. Further evidence for a novel anaerobic biosynthetic pathway to plasmalogens. Biochim Biophys Acta 1811:186-93
Lee, Dong-Woo; El Khoury, Youssef; Francia, Francesco et al. (2011) Zinc inhibition of bacterial cytochrome bc(1) reveals the role of cytochrome b E295 in proton release at the Q(o) site. Biochemistry 50:4263-72
Liu, Zhi; Yang, Menghua; Peterfreund, Gregory L et al. (2011) Vibrio cholerae anaerobic induction of virulence gene expression is controlled by thiol-based switches of virulence regulator AphB. Proc Natl Acad Sci U S A 108:810-5
Selak, Mary A; Lyver, Elise; Micklow, Elizabeth et al. (2011) Blood cells from Friedreich ataxia patients harbor frataxin deficiency without a loss of mitochondrial function. Mitochondrion 11:342-50
Johnston, Norah C; Aygun-Sunar, Semra; Guan, Ziqiang et al. (2010) A phosphoethanolamine-modified glycosyl diradylglycerol in the polar lipids of Clostridium tetani. J Lipid Res 51:1953-61

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