RESEARCH INTERESTS
My major research projects center around mutagenesis studies designed to probe the structure/function of the chlorophyll-binding protein CP 43. CP 43 is a component of the Photosystem II (PSII) complex of higher plants, green algae and cyanobacteria (blue-green algae). CP 43 primarily functions as a chlorophyll-a antenna in PSII, but also appears to have other functions. Its presence is required for oxygen evolution from isolated PSII complexes. CP 43 additionally appears to be required for the proper assembly of PSII components. CP 43 is an integral thylakoid protein; however, it contains a large extrinsic loop region (LEL) that is lumenally oriented. This LEL appears to contain sites that may be involved in PSII structure/function.
We are using oligonucleotide-directed and random mutagenesis to introduce specific base pair changes in regions of the psbC gene encoding the large extrinsic loop of CP 43, in order to test the hypothesis that these sites are involved in the process of oxygen evolution. Our model system is the cyanobacterium Synechocystis 6803. The PSII protein components of Synechocystis and those of higher plants are highly homologous. Additionally, Synechocystis is naturally transformable. These properties make Synechocystis an excellent model system for higher plant photosynthesis. These studies are providing information on which other PSII components CP 43 directly interacts with (via the large extrinsic loop), and what portions of the LEL participate in the various functions of CP 43. This work is supported by a grant from the National Science Foundation. SELECTED PUBLICATIONS Ahn, H.-C., Le, Y. T.-H., Nagchowdhuri, P.S., Derose, E.F., Putnam-Evans, C., London, R.E., Markley, J.L. and Lim, K.H. (2006). NMR Characterization of an Amyloidogenic Conformational Ensemble of the PI3K SH3 Domain. Protein Science, 15:1-6. Ananyev, G., Nguyen, T., Putnam-Evans, C. and Dismukes, C. (2005). Mutagenesis of CP43-Arginine-357 to Serine Reveals New Evidence for (Bi)Carbonate Functioning in the Water Oxidizing Complex of Photosystem II. Photochemical & Photobiological Sciences, 4(12):991-8. Booth, D., Sirochman, R., Richardson, D.C., Richardson, J.S., Weiner, S.W., Farwell, M., Putnam-Evans, C.and Robert C. Bateman Jr. (2005) Assessment of Molecular Construction in Undergraduate Biochemistry. Journal of Chemical Education, 82(12):1584-1588. Bricker, T.M., Young, A., Frankel, L.K., and Putnam-Evans,C. (2002). Introduction of the 305Arg à 305Ser Mutation in the Large Extrinsic Loop E of the CP43 Protein of Synechocystis sp. PCC6803 Leads to the Loss of Cytochrome c550 Binding to Photosystem II. Biochimica Biophysica Acta, 1556:92-96. Young, A., McChargue, M., Frankel, L.K., Bricker, T.M. and Putnam-Evans, C. (2002). Alterations of the Oxygen-Evolving Apparatus Induced by a 305Arg à 305S Mutation in the CP43 Protein of Photosystem II from Synechocystis sp. PCC 6803 under Chloride-Limiting Conditions. Biochemistry, 41:15747-15753. Anderson, L.B., Maderia, M., Ouelette, A.J.A., Putnam-Evans, C., Higgins, L., Krick, T., MacCoss, M.J., Lim, H., Yeats, J.R., and Barry, B.A. (2002) Post-Translational Modifications in the CP43 Subunit of the Photosynthetic Water-Oxidizing Complex. Proc. Natl. Acad. Sci. USA, 99:14676-14681. Rosenberg, Christina, Christian, Julie, Bricker, T.M. and Cindy Putnam-Evans (1999). Site-Directed Mutagenesis of Glutamate Residues in the Large Extrinsic Loop of the Photosystem II Protein CP 43 Affects Oxygen-Evolving Activity and PSII Assembly. Biochemistry, 38:15994-16000. Knoepfle, Nicholas, Bricker, T.M. and Cindy Putnam-Evans (1999). Site-Directed Mutagenesis of Basic Residues 305R and 342R in the CP 43 Protein of Photosystem II Affects Oxygen-Evolving Activity in Synechocystis 6803. Biochemistry, 38:1582 - 1588. COURSES TAUGHT
BIOL 5800 – Biochemistry I (Intermediary Metabolism)
BIOL 5810 – Biochemistry II (Protein Structure/Function)
BIOL 6250/51 – Protein Purification Techniques
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