This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 19/2/625    most recent tpc.106.043125v1 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 ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via ISI Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Wirtz, M. Articles by Hell, R. Search for Related Content PubMed PubMed Citation Articles by Wirtz, M. Articles by Hell, R. Agricola Articles by Wirtz, M. Articles by Hell, R.

Dominant-Negative Modification Reveals the Regulatory Function of the Multimeric Cysteine Synthase Protein Complex in Transgenic Tobacco^[W]

Heidelberg Institute of Plant Sciences, University of Heidelberg, 69120 Heidelberg, Germany

¹ To whom correspondence should be addressed. E-mail rhell{at}hip.uni-heidelberg.de; fax 49-6221-545859.

Cys synthesis in plants constitutes the entry of reduced sulfur from assimilatory sulfate reduction into metabolism. The catalyzing enzymes serine acetyltransferase (SAT) and O-acetylserine (OAS) thiol lyase (OAS-TL) reversibly form the heterooligomeric Cys synthase complex (CSC). Dominant-negative mutation of the CSC showed the crucial function for the regulation of Cys biosynthesis in vivo. An Arabidopsis thaliana SAT was overexpressed in the cytosol of transgenic tobacco (Nicotiana tabacum) plants in either enzymatically active or inactive forms that were both shown to interact efficiently with endogenous tobacco OAS-TL proteins. Active SAT expression resulted in a 40-fold increase in SAT activity and strong increases in the reaction intermediate OAS as well as Cys, glutathione, Met, and total sulfur contents. However, inactive SAT expression produced much greater enhancing effects, including 30-fold increased Cys levels, attributable, apparently, to the competition of inactive transgenic SAT with endogenous tobacco SAT for binding to OAS-TL. Expression levels of tobacco SAT and OAS-TL remained unaffected. Flux control coefficients suggested that the accumulation of OAS and Cys in both types of transgenic plants was accomplished by different mechanisms. These data provide evidence that the CSC and its subcellular compartmentation play a crucial role in the control of Cys biosynthesis, a unique function for a plant metabolic protein complex.

This article has been cited by other articles:

				F. H. Haas, C. Heeg, R. Queiroz, A. Bauer, M. Wirtz, and R. Hell Mitochondrial Serine Acetyltransferase Functions as a Pacemaker of Cysteine Synthesis in Plant Cells Plant Physiology, October 1, 2008; 148(2): 1055 - 1067. [Abstract] [Full Text] [PDF]

				C. Heeg, C. Kruse, R. Jost, M. Gutensohn, T. Ruppert, M. Wirtz, and R. Hell Analysis of the Arabidopsis O-Acetylserine(thiol)lyase Gene Family Demonstrates Compartment-Specific Differences in the Regulation of Cysteine Synthesis PLANT CELL, January 1, 2008; 20(1): 168 - 185. [Abstract] [Full Text] [PDF]

				M. Watanabe, M. Kusano, A. Oikawa, A. Fukushima, M. Noji, and K. Saito Physiological Roles of the -Substituted Alanine Synthase Gene Family in Arabidopsis Plant Physiology, January 1, 2008; 146(1): 310 - 320. [Abstract] [Full Text] [PDF]