Ekaterina V. Pletneva
Associate Professor of Chemistry
Molecular switching mediated by metal ions is an important process in the folding and function of metalloproteins, biological cell signaling, electron transfer and catalysis. When transition metal ions are involved, protein conformational switching affects the metal site's redox activity and conversely redox reactions themselves can act as triggers of protein rearrangements, enabling redox sensing. Despite the prominent role of redox-linked conformational changes in biology, the mechanisms of these transformations are poorly understood. Elucidating the principles that govern these phenomena could provide valuable insights for the design of novel conformational drugs targeting protein redox activity as well as switchable components for molecular electronics and artificial photosynthesis.
Heme proteins are the main subjects of our research. In particular, we have been focusing on ligand substitution reactions at the heme as a common platform for switching the protein structure and redox reactivity in signaling processes (Figure 1). We are investigating conformational properties of cytochrome c in apoptosis and correlate them to the protein peroxidase activity, which is critical for execution of this cellular pathway. We are also studying redox reactivity and folding of native sensors and engineered "switchable" proteins, in which changes in the oxidation state of the heme are linked to heme ligand substitution resulting in protein conformational rearrangements.
We employ a wide range of experimental approaches including various techniques of optical spectroscopy, calorimetry, electrochemistry, mutational studies in vitro and in vivo, as well as development and synthesis of new protein dynamics probes. Measurements of electron- and energy-transfer kinetics allow us to observe and quantitatively characterize conformational transitions, determine structural changes and corresponding energy barriers, as well as evaluate the composition of heterogeneous ensembles. Measurements of protein stability and binding interactions provide a rationale for the observed conformational changes. As these experiments map the entire energy landscape of protein folding and function, they provide a detailed framework for understanding the factors that control protein conformation and redox reactivity.
J. F. Amacher, F. Zhong, G. P. Lisi, M. Q., Zhu, S. L. Alden, K. R. Hoke, D. R. Madden, E. V. Pletneva “A Compact Structure of Cytochrome c Trapped in a Lysine-Ligated State: Loop Refolding and Functional Implications of a Conformational Switch” J. Am. Chem. Soc. 2015, 137, 8435–8449.
C. W. T. Leung, Y. Hong, J. Hanske, E. Zhao, S. Chen, E. V. Pletneva, B. Z. Tang "A superior fluorescent probe for detection of cardiolipin" Anal. Chem. 2014, 86, 1263-8.
J. Gu, S. Yang, A. J. Rajic, I. V. Kurnikov, T. R. Prytkova, E. V. Pletneva "Control of cytochrome c redox reactivity through intraprotein hydrogen-bonding network" Chem. Commun. 2014, 50, 5355-5357.
F. Zhong, G. P. Lisi, D. P. Collins, J. H. Dawson, E. V. Pletneva "Redox-dependent stability, protonation, and reactivity of cysteine-bound heme proteins" Proc. Natl. Acad. Sci. U. S. A. 2014, 111, E306-15.
J. Muenzner, J. R. Toffey, Y. Hong, E. V. Pletneva "Becoming a peroxidase: cardiolipin-induced unfolding of cytochrome c" J. Phys. Chem. B 2013, 117, 12878-12886.
E. J. Snider, J. Muenzner, J. R. Toffey, Y. Hong, E. V. Pletneva "Multifaceted effects of ATP on cardiolipin-bound cytochrome c" Biochemistry 2013, 52, 993-995.
A. J. Vincelli, D. S. Pottinger, F. Zhong, J. Hanske, S. G. Rolland, B. Conradt, E. V. Pletneva "Recombinant expression, biophysical characterization, and cardiolipin-induced changes of two Caenorhabditis elegans cytochrome c proteins" Biochemistry 2013, 52, 653-666.
Y. Hong, J. Muenzner, S. K. Grimm, E. V. Pletneva "Origin of the conformational heterogeneity of cardiolipin-bound cytochrome c" J. Am. Chem. Soc. 2012, 134, 18713-18723.
T. L. Freeman, Y. Hong, K. H. Schiavoni, D. M. I. Bandara, E. V. Pletneva “Changes in the heme ligation during folding of a Geobacter sulfurreducens sensor GSU0935” Dalton. Trans. 2012, 41, 8022-8030.
J. Hanske, J. R. Toffey, A. M. Morenz, A. J. Bonilla, K. H. Schiavoni, E. V. Pletneva “Conformational properties of cardiolipin-bound cytochrome c” Proc. Natl. Acad. Sci. U. S. A. 2012, 109, 125-30.
Works in Progress
“Unraveling Folding Dynamics of Heme Proteins with Fluorescence Energy Transfer Kinetics;” “Comparative Analysis of the Effects of Different Osmolytes on Folding of Drk SH3 Domain”