Holtgrefe, Simone , van der Linde, Karina , Gohlke, Jochen , Wojtera, Joanna , Lindermayr, Christian , Scheibe, Renate .
Cysteine modifications of cytosolic enzymes as a means for signaling redox-imbalances to the nucleus?
Two glycolytic enzymes, namely glyceraldehyde-3-P dehydrogenase (GAPDH; EC 1.2.12) and aldolase (EC 126.96.36.199) were shown to be inactivated by oxidized glutathione and – even more efficiently – by nitrosoglutathione. Incorporation of glutathionyl- and/or nitrosyl-units was shown with various methods. Modification and inactivation were, in most cases, reversible upon incubation with reduced dithiothreitol. Furthermore, the influence of these thiol modifications upon subunit structure and protein conformation was determined. In DNA-binding assays using various fragments of the NADP-malate dehydrogenase gene (At5g58330) these proteins were shown to possess affinity for DNA association. Finally, we could demonstrate a nuclear localization of GFP fusions of cytosolic GAPDH in transiently transformed protoplasts from A. thaliana. All these findings taken together suggest that possibly transcription of various proteins that are required to balance the cellular redox-state upon sustained stress, such as the malate-valve system, is stimulated upon the appearance of oxidatively modified proteins in the cytosol, due to their transfer to the nucleus. Modification of cysteine residues of GAPDH and aldolase might therefore serve two functions: (i) the decrease of glycolysis under stress, and (ii) the nuclear translocation of a portion of these cytosolic proteins to function as transcription activators when long-term acclimation is required. Financial support provided by the DFG (FOR 387) is gratefully acknowledged.
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1 - University of Osnabrueck, FB5/Plant Physiology
2 - GSF, Institute of Biochemical Plant Pathology
3 - University of Osnabrueck, Faculty of Biology and Chemistry, Plant Physiology, Osnabrueck, D-49069, Germany
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM