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ANDREW N. WEBBER Professor Ph.D., University of Essex (England) Phone: (480) 965-8725 Send e-mail to andrew.webber@asu.edu

I came to Arizona State University in 1989 after working on various aspects of photosynthesis and plant molecular biology at the University of California at Berkeley, and the University of Cambridge, U.K. At ASU, our research group has focused on the molecular mechanisms of photosynthetic energy transduction and chloroplast development.

A long-standing project has focused on the structure and function of the photosystem I reaction center complex. The structure of photosystem I is now known at atomic resolution. However, it is still unknown why the electron transfer cofactors have such a remarkably low potential. We use recombinant DNA techniques to specifically alter the genes encoding the photosystem I heterodimer to understand how the protein environment may modulate essential physico-chemical properties of the electron transfer intermediates. As a model organism for these studies we use the eukaryotic green alga Chlamydomonas reinhardtii. The chloroplast genome of Chlamydomonas can be easily transformed using a gene gun to shoot modified genes, carried on sub-micron sized gold particles, into the chloroplast. Mutant cells are produced that synthesize the reaction-center complex with altered polypeptide components. These site-specific mutants of Chlamydomonas are characterized using a range of molecular, biochemical and biophysical techniques.

We also have a productive collaboration with scientists at the US Water Conservation Laboratory investigating the impact of global change on agricultural crop production. Most recently we have investigated the combined effect of elevated atmospheric CO2 and water stress on C4 photosynthesis in sorghum. This project allows students to interact with an international team of scientists who visit the FACE (free atmospheric CO2 enrichment) site and use this unique material for their own research.

Selected Publications

Rajagopal S., Jolley, C., Brune, D., Fromme, P. and Webber, A.N. 2006. Characterization of a novel Photosystem I-LHCI supercomplex isolated from Chlamydomonas reinhardtii under anaerobic (State II) conditions. Federation of European Biochemical Societies Letters, in press.

Li, Y., van der Est, A., Lucas, M.G., Ramesh, V.M., Gu, F., Petrenko, P., Lin, S., Webber, A.N., Rappaport, F., Redding, K. 2006. Directing electron transfer within Photosystem I by breaking H-bonds in the cofactor branches. Proceedings of the National Academy of Sciences, in press

Webber A.N. and Ramesh, V. 2005. Mutagenesis of Ligands to Photosystem I Cofactors Advances in Photosynthesis Research: Photosystem I (Gobeck, J., ed.). Kluwer Academic Publishers, in press.

Austin, J. and Webber, A.N. (2005) Photosynthesis in Arabidopsis thaliana mutants with reduced chloroplast number. Photosynthesis Research, in press.

Ramesh, V.M. Bingham, S.E. and Webber, A.N. (2004) Specific mutagenesis of Photosystem I reaction center proteins by chloroplasts transformation of Chlamydomonas. In: Methods in Molecular Biology, (Carpentier, R., Ed), Humana Press.

Adam N.R., Wall, G.W., Kimball, B.A., Pinter, Jr., P.A., LaMorte. R.L. and Webber, A.N. 2004 Photosynthetic down-regulation over long-term CO2 enrichment in leaves of sour orange (Citrus aurantium) trees. New Phytologist, 163, 341-347.

Webber A.N. 2004. Photosystem II and Photosystem I Structure. In: Encyclopedia of Plant and Crop Science (Goodman, R.M. ed.), Marcel Dekker, Inc. NY. 4pp.

Ramesh, V.M. and Webber, A.N. 2004. Rapid isolation and purification of photosystem I (PSI) chlorophyll - binding protein from Chlamydomonas reinhardtii. In: Methods in Molecular Biology, (Carpentier, R., Ed), Humana Press. In: Methods in Molecular Biology, (Carpentier, R., Ed), Humana Press.

Ramesh, V., Gibasiewicz, K., Lin, S., Scott E. Bingham and Webber, A.N. 2004. Bidirectional electron transfer in photosystem I: accumulation of A0- in A-side and B-side mutants of the axial ligand to chlorophyll A0. Biochemistry, Biochemistry, 43, 1369-1375.

Witt, H., Bordignon, E., Carbonera, D., Dekker, J.P., Karapetyan, N., Teutloff, C., Webber, A., Lubitz, W. and Schlodder, E. 2003. Species specific differences in the spectroscopic properties of P700 investigated by site-directed mutagenesis of photosystem I from Chlamydomonas reinhardtii. Journal of Biological Chemistry, 278, 46760-46771.

Gibasiewicz, K., Ramesh, V., Lin, S., Woodbury, N., and Webber, A.N. 2003. Excitonic interactions in mutant and wildtype photosystem I reaction centers. Biophysical Journal, 85, 2547-2559.

Ramesh, V.M. and Webber, A.N. 2003. Rapid isolation and purification of photosystem I (PSI) chlorophyll - binding protein from Chlamydomonas reinhardtii. In: Methods in Molecular Biology, (Carpentier, R., Ed), Humana Press. In: Methods in Molecular Biology, (Carpentier, R., Ed), Humana Press.

Cousins, A.B., Adam, N.R., Wall, G.W., Kimball, B.A., Pinter, Jr, P.J., Ottman, M.J., Leavitt, S.W., Webber, A.N. 2003. Development of C4 photosynthesis in Sorghum leaves grown under elevated CO2, Journal of Experimental Botany, 54, 1969-1975.

Ramesh, V.M., Guergova-Kuras, M., Joliot, P. and Webber, A.N. 2002. Electron transfer from plastocyanin to the photosystem I reaction center in mutants with increased potential of the primary donor in Chlamydomonas reinhardtii. Biochemistry, 41, 14652-14658.

Cousins, A.B., Adam, N.R., Wall, G.W., Kimball, B.A., Pinter, Jr, P.J., Ottman, M.J., Leavitt, S.W., Webber, A.N. 2002. Photosystem II energy use, non-photochemical quenching and the xanthophyll cycle in Sorghum bicolor grown under drought and Free-Air CO2 Enrichment (FACE) conditions. Plant Cell and Environment, 25, 1551-1559.

Gibasiewicz, K., Ramesh, V., Lin, S., Woodbury, N., and Webber, A.N. 2002. Excitation dynamics in eukaryotic PSI from Chlamydomonas reinhardtii CC 2692 at 10 K. Direct detection of the reaction center exciton states. Journal of Physical Chemistry B, 106, 6322-6330.

Cousins, A.B., Adam, N.R., Wall, G.W., Kimball, B.A., Pinter, Jr., P.P., Leavitt, S.W., LaMorte, R.L., Mathias, A.D., Ottman, M.J., Thompson, T.L. and Webber, A.N. 2001. Response of C4 photosynthesis in sorghum to growth under free-air carbon dioxide enrichment (face): Young leaves exhibit higher rates of photorespiration and decreased energy use efficiency. New Phytologist 150, 275-284.

Wall, G.W., Brookes, T.J., Adam, N.R., Cousins, A.B., Triggs, J., Kimball, B.A., Pinter, Jr., P.J., LaMorte, R.L., Ottman, M.J., Leavitt, S.W., Mathias, A.D., Williams, D.G. and Webber, A.N. 2001. Elevated atmospheric CO2 improved Sorghum plant water status by ameliorating the adverse effects of drought. New Phytologist, 152, 231-248.

Webber, A.N. and Lubitz, W. 2001. The primary electron donor of Photosystem I, P700. Biochimica Biophysica Acta 1507, 61-79.

Gibasiewicz, K., Ramesh, V., Melkozernov, A.N., Lin, S. , Woodbury, N., Blankenship, R. E. and Webber, A.N. 2001. Excitation energy in the core antenna of PSI from Chlamydomonas reinhardtii CC 2692 at room temperature. Journal of Physical Chemistry B105, 11498-11506.

Hastings, G., Ramesh, V., Wang, R., Sivakumar, V. and Webber, A. (2001) Primary donor photo-oxidation in photosystem I: A re-evaluation of (P700+-P700) fourier transform infrared difference spectra. Biochemistry 40, 12943-12949.

Webber, A.N. 2000. Photophosphorylation. In: Encyclopedia of Life Sciences, Macmillan Reference Limited, Stockton Press, 4pp.

Webber, A.N. 2000. Development of the photosynthetic apparatus. In: Leaf Development and Canopy Growth (B. Marshall and J. Roberts, eds.), pp. 145-170, Sheffield Academic Press.

Krabben, L. Schlodder, E., Jordan, R., Carbonera, D., Giacometti, G., Lee, H., Webber, A.N. and Lubitz W. 2000. The Influence of the Axial Ligands on the Spectral Properties of P700 of Photosystem I: A Study of Site-Directed Mutants. Biochemistry, 39, 13012-13025.

Adam N.R., Wall, G.W., Kimball, B.A., Pinter, Jr., P.A., LaMorte. R.L. and Webber, A.N. 2000. Acclimation Response of the Photosynthetic Apparatus in a Wheat Ecosystem Under Free-air CO2 Enrichment (FACE) and Variable Soil Nitrogen Regimes: Leaf Position and Phenology Determine Acclimation Response. Photosynthesis Research, 66, 65-77.

Wall, G.W., Adam, N.R., Brookes, T.J., Kimball, B.A., Pinter, Jr., P.P., LaMorte, R.L., Adamson, F.J., Hunsaker, D.J., Weschsung, G., Weschsung, F., Leavitt, S.W., Mathias, A.D. and Webber, A.N. 2000. Acclimation response of spring wheat in a free-air CO2 enrichment (FACE) atmosphere with variable soil nitrogen regimes: Net assimlation and stomatal conductance of leaves. Photosynthesis Research, 66, 79-95.