Department of Chemistry Biochemistry


Ph.D., Stanford, 1993

  Office: PS D323  Lab: PS D336/332/325
  Phone: (480)965-0136  Lab Phone: (480)965-0182
  Fax: (480) 965-2747

Research and Teaching Interests

The Redding group works on the assembly, function, and degradation of integral membrane proteins involved in energy transduction. 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, which form a framework holding the cofactors involved in electron transport.

1) Structure/function studies: One of the most 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 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.

4) Electron transfer processes in Heliobacteria: Our newest project involves engineering of the most primitive photosynthetic organism currently known. They use a homodimeric reaction center that is superficially similar to PS1 in several ways. The genome of Heliobacterium modesticaldum, the only thermophilic organism in this group, was recently determined in a collaboration between TGen and ASU ( We have recently developed a transformation system for this organism, and are using it to delete key proteins involved in photosynthetic electron transfer and biosynthesis of cofactors. Long-term goals include: gaining insight into the evolution of asymmetric photosynthetic reaction centers, assessing alternative roles for quinones in this group of organisms, and optimizing their production of hydrogen.

Selected Publications

"Species Dependent Alteration of Electron Transfer in Photosystem I," M.D. McConnell, J. Sun, R. Siavashi, A.N. Webber, K.E. Redding, J.H. Golbeck, and A. van der Est, Biochim. Biophys. Acta. 1847 429-440 (2015)

"Controlling electron transfer between the two cofactor chains of Photosystem I by the redox state of one of their components.," S. Santabarbara, B. Bullock, F. Rappaport, K.E. Redding, Biophys. J. 108 1537-1547 (2015)

"Redesigning photosynthesis to sustainably meet global food and bioenergy demand.," D.R. Ort, S.S. Merchant, J. Alric, A. Barkan, R.E. Blankenship, R. Bock, R. Croce, M.R. Hanson, J.M. Hibberd, D.L. Lindstrom, S.P. Long, T.A. Moore, J. Moroney, K.K. Niyogi, M. Parry, P. Peralta-Yahya, R. Prince, K.E. Redding, M.H. Spalding, K. van Wijks, W.F.J. Vermaas, S. von Caemmerer, A.P.M. Weber, T. Yeates, J. Yuan, X. Zhu, Proc Natl Acad Sci USA 112 8529-8536 (2015)

"Expression and characterization of cytochrome c553 from Heliobacterium modesticaldum.," T. Kashey, J.B. Cowgill, M.D. McConnell, M. Flores, K.E. Redding, Photosynth Res 120 291-299 (2014)

"Modulation of the fluorescence yield in Heliobacterial cells by induction of charge recombination in the photosynthetic reaction center. ," K.E. Redding*, I. Sarrou, F. Rappaport, S. Santabarbara, S. Lin, and K. Reifschneider, Photosynth Res 120 221-235 (2014)

"Expression of the [FeFe] hydrogenase in the chloroplast of Chlamydomonas reinhardtii. ," K.T. Reifschneider-Wegner, A. Kanygin, and K.E. Redding, Intl. J. Hydrogen Energy 39 3657-3665 (2014)

"The requirement for carotenoids in the assembly and function of the photosynthetic complexes in Chlamydomonas reinhardtii.," S. Santabarbara, A.P. Casazza, K. Ali, C.K. Economou, T. Wannathong, F. Zito, K.E. Redding, F. Rappaport, and S. Purton, Plant Physiol.: 161 535-46 (2013)

"Temporal and Spectral Characterization of the Photosynthetic Reaction Center from Heliobacterium modesticaldum.," A. Chauvet, I. Sarrou, S. Lin, S. Romberger, J.H. Golbeck, S. Savikhin, K.E. Redding , Photosynth Res 116 1-9 (2013)

"Kinetics of phyllosemiquinone oxidation in the Photosystem I reaction centre of Acaryochloris marina," S. Santabarbara, B. Bailleul, K.E. Redding, J. Barber, F. Rappaport, and A. Telfer, Biochim. Biophys. Acta 1817 328-35 (2012)

"Introduction of a Hydrogen Bond between Phylloquinone PhQA and a Threonine Side-chain OH Group in Photosystem I.," S. Mula, M.D. McConnell, A. Ching, N. Zhao, H.I. Gordon, G. Hastings, K.E. Redding, and A. van der Est, J. Phys. Chem. B 116 14008-16 (2012)

"Alteration of the H-Bond to the A(1A) Phylloquinone in Photosystem I: Influence on the Kinetics and Energetics of Electron Transfer," N. Srinivasan, S. Santabarbara, F. Rappaport, D. Carbonera, K. Redding, A. van der Est, J.H. Golbeck, J. Phys. Chem. B 115 1751-9 (2011)

"Double Reduction of Plastoquinone to Plastoquinol in Photosystem 1," M.D. McConnell, J.B. Cowgill, P.L. Baker, F. Rappaport and K.E. Redding, Biochemistry 50 11034-46 (2011)

"Modulation of fluorescence in Heliobacterium modesticaldum cells. ," A.M. Collins, K.E Redding, and R.E. Blankenship, Photosynth. Res 104 283-92 (2010)

"Inter-quinone electron transfer in Photosystem I as evidenced by altering the hydrogen bond to the phylloquinone(s).," S. Santabarbara, K. Reifschneider, A. Jasaitis, F. Gu, G. Agostini, D. Carbonera, F. Rappaport, K.E. Redding., J. Phys. Chem. B 114 9300-12 (2010)

"Independent initiation of primary electron transfer in the two branches of the Photosystem I reaction center.," M.G. Muller, C. Slavov, R. Luthra, K.E. Redding* and Alfred R. Holzwarth, Proc. Natl. Acad. Sci. USA 107 4123-8 (2010)

"Temperature dependence of the reduction of P700+ by tightly bound plastocyanin in vivo.," S. Santabarbara, K.E. Redding, F. Rappaport, Biochemistry 48 10457-66 (2009)

"Additive Effect of Mutations Affecting the Rate of Phylloquinone Reoxidation and Directionality of Electron Transfer within Photosystem I. , ," S. Santabarbara, A. Jasaitis, F. Gu, F. Rappaport, K.E. Redding, Photochem. Photobiol. 84 1381-7 (2008)

"Purification of His6-tagged Photosystem I from Chlamydomonas reinhardtii," Gulis, G., K. V. Narasimhulu, L.N. Fox, and K.E. Redding, Photosynth. Res. 92 51-60 (2007)

"Mycobacterium tuberculosis WhiB3 responds to dormancy signals through its [4Fe-4S] cluster," Singh, A., L. Guidry, K. V. Narasimhulu, J. Trombley, K.E. Redding, G.I. Giles, J. Lancaster Jr, and A.J.C. Steyn, Proc. Natl. Acad. Sci. USA 104 11562-7 (2007)

"Two equilibration pools of chlorophylls in the PSI core antenna," Gibasiewicz, K., V.M. Ramesh, S. Lin, K. Redding, N.W. Woodbury, and A.N. Webber, Photosynth. Res. 92 55-63 (2007)

"Assignment of a kinetic component to electron transfer between iron-sulfur clusters FX and FA/B of Photosystem I," Byrdin, M., Santabarbara, S., Gu, F., Fairclough, W., Heathcote, P., Redding, K. and Rappaport, F., Biochim. Biophys. Acta, 1757 1529-38 (2006)

"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)

"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)

"Mutation of the putative hydrogen-bond donor to P700of 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)

"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)

"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)

"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)

"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)