Aileen Taguchi

Faculty Research Associate
Department of Chemistry and Biochemistry

serpent drawing Research Interests:

The photosynthetic reaction center from purple sulfur bacteria provides a flexible and sensitive system to examine how a large protein-pigment complex is produced. Both genetic and physical maps of the chromosome have recently been completed, facilitating genetic studies of the regulation of photosynthetic gene function and assembly. The three-dimensional X-ray crystal structure for the reaction center has also been solved, allowing visualization of the interactions holding this complex together. The Photosynthesis Center laser facility provides state-of-the-art spectroscopic tools for probing reaction center function.

The reaction center core is composed of three proteins, six bacteriochlorin pigment molecules, and a nonheme iron atom. The process by which the DNA gene sequences encoding the protein subunits are activated and translated into the unfolded protein subunits is well on the way to being understood. The following steps during which the protein, pigment, and iron all coalesce into a functional multipartite whole in a membrane environment remains a mystery. Our laboratory has selected several mutations which may be involved in the latter assembly process. These mutations allow expression of even suboptimal mutant versions of the reaction center. Our goal is to clone some of these mutations and to examine the function of wild type and mutant versions of these genes. Further study of this bank of mutants will provide new information on the various steps involved in protein folding, pigment insertion, integration of the complex into its natural membrane environment, and stabilization of the final complex.

Recent Publications:

Williams, J.C. and Taguchi, A.K.W. (1995) Genetic manipulation of purple photosynthetic bacteria. In: Anoxygenic Photosynthetic Bacteria, Blankenship R.E., Madigan M.T. and Bauer C.E. (eds), pp 10291065. Kluwer Academic Publishers, Dordrecht.

Peloquin, J.M., Williams, J.C., Lin, X., Alden, R.G., Murchison, H.A., Taguchi, A.K.W., Allen, J.P. and Woodbury, N.W. (1994) Time-dependent thermodynamics during early electron transfer in reaction centers from Rhodobacter sphaeroides. Biochemistry 33: 80898100.

Xiao, W., Lin, S., Taguchi, A.K.W. and Woodbury, N.W. (1994) Femtosecond pump-probe analysis of energy and electron transfer in photosynthetic membranes of Rhodobacter capsulatus. Biochemistry 33: 83138322.

Taguchi, A.K.W., Stocker, J.W., Boxer, S.G. and Woodbury, N.W. (1993) Photosynthetic reaction center mutagenesis via chimeric rescue of a non-functional Rhodobacter capsulatus puf operon with sequences from Rhodobacter sphaeroides. Photosynth. Res. 36: 4358.

Taguchi, A.K.W., Stocker, J.W., Alden, R.G., Causgrove, T.P., Peloquin, J.M., Boxer, S.G. and Woodbury, N.W. (1992) Biochemical characterization and electron-transfer reactions of sym1, a Rhodobacter capsulatus reaction center symmetry mutant which affects the initial electron donor. Biochemistry 31: 1034510355.