tailieunhanh - Báo cáo khoa học: Regulation of pyruvate dehydrogenase complex activity in plant cells

The pyruvate dehydrogenase complex (PDC) is subjected to multiple interacting levels of control in plant cells. The first level is subcellular compartmentation. Plant cells are unique inhaving twodistinct, spatially separated forms of the PDC; mitochondrial (mtPDC) and plastidial (plPDC). The mtPDCis the site of carbon entry into the tricarboxylic acid cycle, while the plPDCprovides acetyl-CoAandNADHfor de novofatty acid biosynthesis. | Eur. J. Biochem. 270 1043-1049 2003 FEBS 2003 doi MINIREVIEW Regulation of pyruvate dehydrogenase complex activity in plant cells Alejandro Tovar-Mendez1 Jan A. Miernyk1 2 and Douglas D. Randall1 1Department of Biochemistry University of Missouri Columbia USA 2Plant Genetics Research Unit USDA Agricultural Research Service Columbia USA The pyruvate dehydrogenase complex PDC is subjected to multiple interacting levels of control in plant cells. The first level is subcellular compartmentation. Plant cells are unique in having two distinct spatially separated forms of the PDC mitochondrial mtPDC and plastidial plPDC . The mtPDCis the site of carbon entry into the tricarboxylic acid cycle while the plPDC provides acelyl-CoA add NAD H for de novo fatty acid biosynthesis. The second level of regulation of PDCactivity is the control of gene expression. The genes encoding the subunits of the mt- and plPDCs are expressed following developmental programs and are additionally subject to physiological and environmental cues. Thirdly both the mt- and plPDCs are sensitive to product inhibition and potentially to metabolite effectors. Finally the two different forms of the complex are regulated by distinct organelle-specific mechanisms. Activity of the mtPDC is regLlkited by reversible phosphorykition catalysed by intrinsic kinase and phosphatase components. An additional level of sensitivity is provided by metabolite control of the kinase activity. The plPDCis not regulated by reversible phosphorylation. Instead activity is controlled to a large extent by the physical environment that exists in the plastid stroma. Keywords complex chloroplast enzymology localization metabolic regulation mitochondria phosphorylation. Introduction The pyruvate dehydrogenase complex PDC is a multienzyme complex catalyzing the oxidative decarboxylation of pyruvate to yield acetyl-CoA and NADH. The plant PDCs occupy strategic and overlapping positions in plant .