OPEN ACCESS ARTICLE

This Article Free via Open Access: OA OA Full Text Full Text (PDF) Supplemental Data OA All Versions of this Article: 150/2/552    most recent pp.109.135426v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Park, S. K. Articles by Lee, S. Y. Search for Related Content PubMed PubMed Citation Articles by Park, S. K. Articles by Lee, S. Y. Agricola Articles by Park, S. K. Articles by Lee, S. Y.

BIOCHEMICAL PROCESSES AND MACROMOLECULAR STRUCTURES

Heat-Shock and Redox-Dependent Functional Switching of an h-Type Arabidopsis Thioredoxin from a Disulfide Reductase to a Molecular Chaperone^{1,[C],[W],[OA]}

Environmental Biotechnology National Core Research Center, Plant Molecular Biology and Biotechnology Research Center (S.K.P., Y.J.J., J.R.L., Y.M.L., H.H.J., S.S.L., J.H.P., S.Y.K., J.C.M., S.Y.L., H.B.C., M.R.S., J.H.J., W.Y.K., D.-J.Y., K.O.L., S.Y.L.), and Division of Applied Life Science (BK21 program; S.K.P., Y.J.J., J.R.L., Y.M.L., S.S.L., J.H.P., S.Y.K., J.C.M., S.Y.L., H.B.C., M.R.S., J.H.J., D.-J.Y., K.O.L., S.Y.L.), Gyeongsang National University, Jinju 660–701, Korea; Lee Gil Ya Cancer and Diabetes Institute, Gachon University of Medicine and Science, Incheon 406–840, Korea (H.H.J.); Department of Functional Crop, National Institute of Crop Science, Rural Development Administration, Milyang 627–130, Korea (S.K.P.); and Bio-crops Development Division, National Academy of Agricultural Science, Rural Development Administration, 224 Suin-ro, Suwon 441–857, Korea (M.G.K.)

A large number of thioredoxins (Trxs), small redox proteins, have been identified from all living organisms. However, many of the physiological roles played by these proteins remain to be elucidated. We isolated a high M_r (HMW) form of h-type Trx from the heat-treated cytosolic extracts of Arabidopsis (Arabidopsis thaliana) suspension cells and designated it as AtTrx-h3. Using bacterially expressed recombinant AtTrx-h3, we find that it forms various protein structures ranging from low and oligomeric protein species to HMW complexes. And the AtTrx-h3 performs dual functions, acting as a disulfide reductase and as a molecular chaperone, which are closely associated with its molecular structures. The disulfide reductase function is observed predominantly in the low M_r forms, whereas the chaperone function predominates in the HMW complexes. The multimeric structures of AtTrx-h3 are regulated not only by heat shock but also by redox status. Two active cysteine residues in AtTrx-h3 are required for disulfide reductase activity, but not for chaperone function. AtTrx-h3 confers enhanced heat-shock tolerance in Arabidopsis, primarily through its chaperone function.

² These authors contributed equally to the article.

The author responsible for the distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Sang Yeol Lee (sylee{at}gnu.ac.kr).

^[C] Some figures in this article are displayed in color online but in black and white in the print edition.

^[W] The online version of this article contains Web-only data.

^[OA] Open access articles can be viewed online without a subscription.

www.plantphysiol.org/cgi/doi/10.1104/pp.109.135426

^* Corresponding author; e-mail sylee{at}gnu.ac.kr.

Received January 8, 2009; accepted March 26, 2009; published April 1, 2009.