KEVIN E. REDDING Associate Professor   BIOCHEMISTRY/MOLECULAR BIOLOGY biological electron transfer, photosynthesis, assembly and degradation of membrane proteins BA, 1987, Rice University; Ph.D., 1993, Stanford University; NSF Postdoctoral Fellow, 1994-98, University of Geneva office: 343B Shelby Hall Telephone: (205) 348-8430 fax (205) 348-9104 Dr. Redding's home page PDF version of Dr. Redding's research interests

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Research Interests

We are interested in the assembly, function, and degradation of integral membrane proteins. As a model system, we are using Photosystem 1 (PS1), a multi-subunit membrane protein complex that uses the energy of absorbed photons to promote transmembrane electron transfer. The core of PS1 is a heterodimer of two homologous, integral membrane polypeptides (PsaA and PsaB), each of which contains 11 transmembrane a-helices that form a framework holding the cofactors involved in electron transport.

(1) Structure/function studies: One of the interesting questions in biochemistry is "How does the protein environment affect the properties of bound molecules?" The phylloquinone cofactor embedded in PS1 is an excellent example. It is much more reducing when bound in PS1 than when isolated in organic solvent. Thus, the protein is able to "tune" the properties of the quinone so that it functions as a good intermediate in electron transfer. We are using site-directed mutagenesis to change amino acid residues that interact with the phylloquinone, and thus change its properties. Characterization of the mutants involves use of advanced techniques, such as electron paramagnetic resonance and fast kinetic spectroscopy.

(2) Engineering electron transfer: The symmetric structure of PS1 includes two possible pathways of electron transfer. By changing amino acids around one quinone or the other, we have shown that both pathways can be used. We are altering the two quinone sites to see how the differences between them translate into different electron transfer rates. We hope to alter the sites enough to allow binding of alternate target molecules, which may lead to light-powered biomolecular devices capable of reductively destroying environmental pollutants, etc. We are also trying to see if we can control which pathway the electrons take by modify the environment near the electron donors.

(3) Degradation of membrane proteins: Biological systems target aberrant membrane complexes for destruction. Although some human diseases are caused by this process, the systems that recognize and degrade aberrant membrane proteins remain largely unknown. In order to identify these in the chloroplast of green plants, a two-pronged attack is being used: a genetic approach to screen for mutants defective in degradation of PS1, and a biochemical approach to characterize and purify the proteins involved in the degradation process.

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Representative Publications

“Directing electron transfer within Photosystem I by breaking H-bonds in the cofactor branches.” Li, Y., A. van der Est, M. Gabrielle Lucas, V.M. Ramesh, Feifei Gu, A. Petrenko, S. Lin, A.N. Webber, F. Rappaport, and K. Redding. Proc. Natl. Acad. Sci. USA, 103, 2144-9 (2006).

"The influence of the structure of the radical cation dimer pair of aromatic molecules on the principal values of a g-tensor: DFT predictions.” Petrenko, A., K. Redding, and L. Kispert, Chem. Phys. Lett. 406, 327-331 (2005).

"Intermolecular Electron Transfer and Exchange Integrals in Photosystem I.” Petrenko, A. and K. Redding, Chem. Phys. Lett. 400, 98-103 (2004).

"Remodeling of light harvesting protein complexes in Chlamydomonas in response to environmental changes.” Nield, J., K. Redding and M. Hippler, Eukaryotic Cell 3, 1370-80 (2004).

"A high-field EPR study of P₇₀₀^+* in wild-type and mutant Photosystem I from Chlamydomonas reinhardtii." O. Petrenko, A..L Maniero, J. van Tol, F. MacMillan, Y. Li, L.-C. Brunel, and K. Redding, Biochemistry, 43, 1781-1786 (2004).

"Mutation of the putative hydrogen-bond donor to P₇₀₀ of Photosystem I.” Li, Y., M.-G. Lucas, T. Konovalova, B. Abbott, F. MacMillan, A. Petrenko, V. Sivakumar, R. Wang, G. Hastings, F. Gu, J. van Tol, L.-C. Brunel, R. Timkovich, F. Rappaport, and K. Redding. Biochemistry 43, 12634-47 (2004).

"Disassembly and Degradation of Photosystem I in an in vitro System are Multievent, Metal-Dependent Processes," Henderson J.N., Zhang J.Y., Evans B.W., Redding K., J. Biol. Chem. 278, 39978-39986 (2003).

"Evidence for two active branches for electron transfer in photosystem I," Guergova-Kuras, M., Boudreaux, B., Joliot, A., Joliot, P., and Redding, K. Proc. Natl. Acad. Sci. USA, 98, 4437-4442 (2001).

"Mutations in both sides of the Photosystem I reaction center identify the phylloquinone observed by electron paramagnetic resonance spectroscopy," B. Boudreaux, F. MacMillan, C. Teutloff, R. Agalarov, F. Gu, S. Grimaldi, R. Bittl, K. Brettel, and K. Redding. J. Biol. Chem., 276, 37299-37306 (2001).

Book chapter:

“The Directionality of Electron Transfer in Photosystem I .“ Redding, K. and A. van der Est. In Photosystem I: The Plastocyanin:Ferredoxin Oxidoreductase in Photosynthesis. J. Golbeck (ed.), Kluwer Academic Publishers, Dordrecht. (2006).

“Optical measurements of secondary electron transfer in Photosystem I.” F. Rappaport, B. Diner, and K. Redding. In Photosystem I: The Plastocyanin:Ferredoxin Oxidoreductase in Photosynthesis. J. Golbeck (ed.), Kluwer Academic Publishers, Dordrecht. (2006).

Complete list of Dr. Redding's publications (1/29/07)