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.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM038237-25
Application #
8197895
Study Section
Macromolecular Structure and Function A Study Section (MSFA)
Program Officer
Anderson, Vernon
Project Start
1987-12-01
Project End
2013-11-30
Budget Start
2011-12-01
Budget End
2012-11-30
Support Year
25
Fiscal Year
2012
Total Cost
$475,398
Indirect Cost
$160,380
Name
University of Pennsylvania
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Trasnea, Petru-Iulian; Utz, Marcel; Khalfaoui-Hassani, Bahia et al. (2016) Cooperation between two periplasmic copper chaperones is required for full activity of the cbb3 -type cytochrome c oxidase and copper homeostasis in Rhodobacter capsulatus. Mol Microbiol 100:345-61
Khalfaoui-Hassani, Bahia; Verissimo, Andreia F; Koch, Hans-Georg et al. (2016) Uncovering the Transmembrane Metal Binding Site of the Novel Bacterial Major Facilitator Superfamily-Type Copper Importer CcoA. MBio 7:e01981-15
Francia, Francesco; Malferrari, Marco; Lanciano, Pascal et al. (2016) The cytochrome b Zn binding amino acid residue histidine 291 is essential for ubihydroquinone oxidation at the Qo site of bacterial cytochrome bc1. Biochim Biophys Acta 1857:1796-1806
Verissimo, Andreia F; Shroff, Namita P; Daldal, Fevzi (2015) During Cytochrome c Maturation CcmI Chaperones the Class I Apocytochromes until the Formation of Their b-Type Cytochrome Intermediates. J Biol Chem 290:16989-7003
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Ekici, Seda; Turkarslan, Serdar; Pawlik, Grzegorz et al. (2014) Intracytoplasmic copper homeostasis controls cytochrome c oxidase production. MBio 5:e01055-13
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
Yıldız, Gülgez Gökçe; Gennis, Robert B; Daldal, Fevzi et al. (2014) The K(C) channel in the cbb3-type respiratory oxygen reductase from Rhodobacter capsulatus is required for both chemical and pumped protons. J Bacteriol 196:1825-32
Verissimo, Andreia F; Mohtar, Mohamad A; Daldal, Fevzi (2013) The heme chaperone ApoCcmE forms a ternary complex with CcmI and apocytochrome c. J Biol Chem 288:6272-83
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

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