Oxidation/reduction (redox) chemistry of iron-protoporphyrin IX (heme) is central to many fundamental biological processes including energy transduction, redox catalysis, sensing, and signaling. Although there have been many studies of structure-function relationships in heme proteins, the relationship between heme protein dynamics and function has received little attention. In addition, our understanding of how redox- dependent biophysical properties of heme proteins impact electron transfer is not well developed. In this project, we will investigate how cytochrome c (cyt c) structural mobility modulates heme redox function. Cyts c are ubiquitous proteins displaying a range of redox-related functions. They are characterized by the covalent means of heme attachment to the polypeptide, usually to two Cys residues in a Cys-X-X-Cys-His motif. Cyts c span a larger range of potentials (from -412 to +450 mV vs. NHE) relative to cyts b (-130 to +390 mV vs. NHE), which have the same heme cofactor but lack covalent bonds to the polypeptide. To date, an explanation for this variation in range of potentials, and the ability of heme c to access extremely low potentials, has not been made. The means of attachment of heme c to the polypeptide impart on it unique structural and dynamical properties. Data on structure and redox potential described herein present a compelling case that the specific properties of heme c play an important if indirect role in redox potential tuning;we propose that the local structure and fluctuations about the c-heme motif tune iron-ligand interactions and thus redox potential. In addition, we will explore how control of the conformation of the protoporphyrin IX macrocycle itself by the c-heme attachment contributes to redox potential tuning. Cytochromes play vital roles in energy transduction in mitochondria, bacteria, and chloroplasts, as well as many archaea. Such processes are a significant source of reactive oxygen species (ROS), which are a major contributing factor to diseases associated with aging. To develop a complete understanding of events contributing to aging and cell death, and to the development and progression of a range of diseases, the fundamentals of redox chemistry in the cell must be understood. Elucidating basic mechanisms controlling biological redox chemistry is therefore of fundamental importance to biomedical sciences and human health.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM063170-09
Application #
7780351
Study Section
Special Emphasis Panel (ZRG1-BCMB-B (02))
Program Officer
Wehrle, Janna P
Project Start
2001-04-01
Project End
2012-03-31
Budget Start
2010-04-01
Budget End
2012-03-31
Support Year
9
Fiscal Year
2010
Total Cost
$245,184
Indirect Cost
Name
University of Rochester
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
041294109
City
Rochester
State
NY
Country
United States
Zip Code
14627
Galinato, Mary Grace I; Bowman, Sarah E J; Kleingardner, Jesse G et al. (2015) Effects of protein structure on iron-polypeptide vibrational dynamic coupling in cytochrome c. Biochemistry 54:1064-76
Sun, Yuhan; Benabbas, Abdelkrim; Zeng, Weiqiao et al. (2014) Investigations of heme distortion, low-frequency vibrational excitations, and electron transfer in cytochrome c. Proc Natl Acad Sci U S A 111:6570-5
Josephs, Tracy M; Liptak, Matthew D; Hughes, Gillian et al. (2013) Conformational change and human cytochrome c function: mutation of residue 41 modulates caspase activation and destabilizes Met-80 coordination. J Biol Inorg Chem 18:289-97
Can, Mehmet; Krucinska, Jolanta; Zoppellaro, Giorgio et al. (2013) Structural characterization of nitrosomonas europaea cytochrome c-552 variants with marked differences in electronic structure. Chembiochem 14:1828-38
Kaur, Ravinder; Bren, Kara L (2013) Redox state dependence of axial ligand dynamics in Nitrosomonas europaea cytochrome c552. J Phys Chem B 117:15720-8
Lee, Andrea J; Asher, Wesley B; Stern, Harry A et al. (2013) Single-Molecule Analysis of Cytochrome c Folding by Monitoring the Lifetime of an Attached Fluorescent Probe. J Phys Chem Lett 4:2727-2733
Kleingardner, Jesse G; Bowman, Sarah E J; Bren, Kara L (2013) The influence of heme ruffling on spin densities in ferricytochromes c probed by heme core 13C NMR. Inorg Chem 52:12933-46
Galinato, Mary Grace I; Kleingardner, Jesse G; Bowman, Sarah E J et al. (2012) Heme-protein vibrational couplings in cytochrome c provide a dynamic link that connects the heme-iron and the protein surface. Proc Natl Acad Sci U S A 109:8896-900
Levin, Benjamin D; Can, Mehmet; Bowman, Sarah E J et al. (2011) Methionine ligand lability in bacterial monoheme cytochromes c: an electrochemical study. J Phys Chem B 115:11718-26
Chung, Jean K; Thielges, Megan C; Bowman, Sarah E J et al. (2011) Temperature dependent equilibrium native to unfolded protein dynamics and properties observed with IR absorption and 2D IR vibrational echo experiments. J Am Chem Soc 133:6681-91

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