Bob B Buchanan

Professor
Ph.D.  Microbiology    Duke University, 1962
B.A.  Emory and Henry College, 1958

411 Koshland Hall
Berkeley, California 94720-3102
view@berkeley.edu
office: 510-642-3590   lab: 510-642-9799   fax:  510-642-7356

CV       Recent publications      People

Research in the Buchanan Laboratory focuses on thioredoxin--a regulatory protein found in all types of living cell. Plants contain different types of thioredoxin, distributed throughout the plant.



We study the role of thioredoxin and related proteins in two areas.

We study regulation of chloroplast enzymes, emphasizing both the stroma and thylakoid lumen. This research is carried out in collaboration with Sheng Luan.

Recent research uncovered a previously unrecognized role of thioredoxin in regulating cysteine biosynthesis in association with a cyclophilin when plants are exposed to oxidative stress. In this as in other links to enzymes, thioredoxin acts as an eye for the chloroplast allowing biochemical processes of the organelle to adjust and make optimal use of available resources.



We have also uncovered a paradigm for redox regulation in photosynthesis in the thylakoid lumen. In contrast to the stroma, where the activation of enzymes is achieved by a reduction of disulfide groups conversion of (S-S to SH), activation in the lumen occurs in concert with oxygen evolution by the oxidation of sulhydryl groups (conversion of SH to S-S). The latter mechanism shows promise in the commercial production of disulfide-rich value-added proteins.

We have ongoing collaborations with several colleagues on projects to improve the quality and yield of cereals: Peggy G. Lemaux (UC Berkeley); Jun Yin and his group (Henan Agricultural University, Zhengzhous, China); and William J. Hurkman and William H. Vensel (USDA Laboratory, Albany, CA).

The grain harvested from the fields shown below displays improved properties. For barley, accelerated germination. For wheat, decreased allergenicity.





Studies with Dr. Salekdeh and his collaborators in Iran have uncovered a role for thioredoxin and redox in enabling wheat to survive drought conditions.



Recent studies in our laboratory have demonstrated that amylplasts of sink tissues contain a complete ferredoxin/thioredoxin system that regulates fundamental processes in the organelle. In this case, the signal is not light, but the increase in NADPH that results form the breakdown of increased sucrose arriving from the phloem when leaves are illuminated.



In effect, thioreodoxin of amyloplasts acts as a second eye in regulating processes of that plastid.



The amyloplast thioredoxin system complements the role of extraplastidic thioredoxin, that among other functions, acts as a signal in seed germination and seedling development.



In short, as established for chloroplasts, thioredoxin plays a fundamental role in a growing number of processes in heterotrophic plant tissues.

Wong, J.H., Kim, Y.-B., Ren, P.-H., Cai, N., Cho, M.-J., Hedden, P., Lemaux, P.G. and Buchanan, B.B. (2002) Transgenic barley grain overexpressing thioredoxin shows evidence of communication between the endosperm and the embryo and aleurone. Proc. Natl. Acad. Sci. USA 99, 16325-16330.

Marx, C., Wong, J.H. and Buchanan, B.B. (2003) Thioredoxin and germinating barley: targets and protein redox changes. Planta 216, 454-460.

Balmer, Y., Koller, A., del Val, G., Manieri, W., Schürmann, P. and Buchanan, B.B. (2003) Proteomics gives insight into the regulatory function of chloroplast thioredoxins. Proc. Natl. Acad. Sci. USA 100, 370-375.

Wong, J.H., Balmer, Y., Cai, N., Tanaka, C.K., Vensel, W.H., Hurkman, W.J. and Buchanan, B.B. (2003) Unraveling thioredoxin-linked metabolic processes of cereal starchy endosperm using proteomics. FEBS Lett. 547, 151-156.

Kim, Y.B., Garbisu, C., Pickering, I.J., Prince, R.C., George, G.N., Cho, M.-J., Wong, J.H. and Buchanan, B.B. (2003) Thioredoxin h overexpressed in barley seeds enhances selenite resistance and uptake during germination and early seedling development. Planta 218, 186-191.

Balmer, Y., Koller, A., del Val, G., Schürmann, P. and Buchanan, B.B. (2004) Proteomics uncovers proteins interacting electrostatically with thioredoxin in chloroplasts. Photosyn. Res. 79, 275-280. (Special Issue to honor P. Schürmann and M. Miginiac-Maslow on their retirement.)

Wong, J.H., Cai, N., Tanaka, C.K., Vensel, W.H., Hurkman, W.J. and Buchanan, B.B. (2004) Thioredoxin reduction alters the solubility of proteins of wheat starchy endosperm: An early event in germination. Plant Cell Physiol. 45, 407-415. (Dedicated to K. Wada on his retirement from Kanazawa University.)

Balmer, Y., Vensel, W.H., Tanaka, C.K., Hurkman, W.J., Gelhaye, E., Rouhier, N., Jacquot, J.-P., Manieri, W., Schürmann, P., Droux, M. and Buchanan, B.B. (2004) Thioredoxin links redox to the regulation of fundamental processes of plant mitochondria. Proc. Natl. Acad. Sci. USA 101, 2642-2647.

Cho, M.J., Yano, H., Okamoto, D., Kim, H.K., Jung, H.R., Newcomb, K., Le, V.K., Yoo, H.S., Langham, R., Buchanan, B.B. and Lemaux, P.G. (2004) Stable transformation of rice (Oryza sativa L.) via microprojectile bombardment of highly regenerative tissues derived from mature seed. Plant Cell Rep. 22, 483-490.

Wong, J.H., Cai, N., Balmer, Y., Tanaka, C.K., Vensel, W.H., Hurkman, W.J. and Buchanan, B.B. (2004) Identification of thioredoxin targets in developing wheat seeds using complementary proteomic approaches. Phytochem. 65, 1629-1640. (Special Proteomics Issue.)

Vensel, W.H., Tanaka, C.K., Cai, N., Wong, J.H., Buchanan, B.B. and Hurkman, W.J. (2004) Developmental changes in the metabolic protein profiles of wheat endosperm. Proteomics 5, 1594-1611.

Gopalan, G., He, Z., Balmer, Y., Romano, P., Gupta, R., Héroux, A., Buchanan, B.B., Swaminathan, K. and Luan, S. (2004) Structural analysis uncovers a role for redox in regulating FKBP13, an immunophilin of the chloroplast thylakoid lumen. Proc. Natl. Acad. Sci. USA 101, 3945-3950.

Frick, O.L., Teuber, S.S., Buchanan, B.B., Morigasaki, S. and Umetsu, D.T. (2005) Allergen immunotherapy with heat-killed Listeria monocytogenes (HKL) alleviates peanut and food-induced anaphylaxis in dogs. Allergy 60, 243-250.

Vensel, W.H., Tanaka, C.K., Cai, N., Wong, J.H., Buchanan, B.B. and Hurkman, W.J. (2005) Developmental changes in the metabolic protein profiles of wheat endosperm. Proteomics. 5, 1594-1611.

Balmer, Y., Vensel, W.H., Dupont, F.M., Buchanan, B.B., Hurkman, W.J. (2006) Proteome of amyloplasts isolated from developing wheat endosperm presents evidence of broad metabolic capability. J Exp Bot. 57, 1591-1602.

Balmer, Y., Vensel, W.H., Cai, N., Manieri, W., Schurmann, P., Hurkman, W.J., Buchanan, B.B. (2006) A complete ferredoxin/thioredoxin system regulates fundamental processes in amyloplasts. Proc Natl Acad Sci USA 103, 2988-2993.

Balmer, Y., Vensel, W.H., Hurkman, W.J. and Buchanan, B.B. (2006) Thioredoxin target proteins in chloroplast thylakoid membranes. Antioxid. Redox Signal 8, 1829-2834.

Sokolov, L.N., Dominguez-Solis, J.R., Allary, A.-L., Buchanan, B.B. and Luan, S. (2006) A redox-regulated protein phosphatase binds to starch diurnally and function in its accumulation. Proc Natl Acad Sci USA 103, 9732-9737.

Lima, A., Lima, S., Phillips, R.S., Wong, J.H., Buchanan, B.B. and Luan, S. (2006) A redox-active FKBP-type immunophiln functions in photosystem II assembly in chloroplasts of Arabidopsis thaliana. Proc Natl Acad Sci USA 103, 12631-12636.

Hajheidari, M., Eivazi, A., Buchanan, B.B., Wong, J.H., Majidi, I. and Salekdeh, G.H. (2007) Proteomics uncovers a role for redox in drought tolerance in wheat. J. Proteome Res. 6, 1451-1460.

Alkhalfioui, F., Renard, M., Vensel, W.H., Wong, J., Tanaka, C.K., Hurkman, W.J., Buchanan, B.B. and Montrichard, F. (2007) Thioredoxin-linked proteins are reduced during germination of Medicago truncatula seeds. Plant Physiol. 144, 1559-1579.

Buchanan BB. (2007) Thioredoxin: an unexpected meeting place. Photosynth Res. 92:145-148.

Lee SC, Lan WZ, Kim BG, Li L, Cheong YH, Pandey GK, Lu G, Buchanan BB, Luan S. (2007) A protein phosphorylation/dephosphorylation network regulates a plant potassium channel. Proc Natl Acad Sci U S A. 104:15959-15964.

Fu A, He Z, Cho HS, Lima A, Buchanan BB, Luan S. (2007) A chloroplast cyclophilin functions in the assembly and maintenance of photosystem II in Arabidopsis thaliana. Proc Natl Acad Sci U S A. 104:15947-15952.

Lichtenthaler HK, Buchanan BB, Douce R. (2008) Honoring Andrew Benson in Paris : a tribute on his 90th birthday. Photosynth Res. 96:181-183.

Schürmann P, Buchanan BB. (2008) The ferredoxin/thioredoxin system of oxygenic photosynthesis. Antioxid Redox Signal. 10:1235-1274.

Wong, J.H. Tsang, L., Cai, N., Singh, J., Pedersen. J.F., Vensel, W. H., William J. Hurkman, W. J., Wilson, J.D., Lemaux, P.G. and Buchanan, B.B. (2008) Digestibility of Protein and Starch from Sorghum (Sorghum bicolor) is linked to biochemical and structural features of grain endosperm. J. Cereal Sci. In press.

Dominguez-Solis, J.R, He, Z., Lima, A., Ting, J., Buchanan, B.B., and Luan, S. (2008) A cyclophilin links redox and light signals to cysteine biosynthesis and stress responses in chloroplasts. Proc. Natl. Acad. Sci. USA. In press.