31 research outputs found
Mild reductions in cytosolic NADP-dependent isocitrate dehydrogenase activity result in lower amino acid contents and pigmentation without impacting growth
Transgenic tomato (Solanum lycopersicum) plants were generated targeting the cytosolic NADP-dependent isocitrate dehydrogenase gene (SlICDH1) via the RNA interference approach. The resultant transformants displayed a relatively mild reduction in the expression and activity of the target enzyme in the leaves. However, biochemical analyses revealed that the transgenic lines displayed a considerable shift in metabolism, being characterized by decreases in the levels of the TCA cycle intermediates, total amino acids, photosynthetic pigments, starch and NAD(P)H. The plants showed little change in photosynthesis with the exception of a minor decrease in maximum photosynthetic efficiency (Fv/Fm), and a small decrease in growth compared to the wild type. These results reveal that even small changes in cytosolic NADP-dependent isocitrate dehydrogenase activity lead to noticeable alterations in the activities of enzymes involved in primary nitrate assimilation and in the synthesis of 2-oxoglutarate derived amino acids. These data are discussed within the context of current models for the role of the various isoforms of isocitrate dehydrogenase within plant amino acid metabolism
Impact of invertase overexpression on cell size, starch granule formation and cell wall properties during tuber development in potatoes with modified carbon allocation patterns
Use of Transgenic Potato Plants to Analyze Physiological and Structural-Changes during Tuber Development
Regulation and structure of YahD, a copper inducible alpha beta hydrolase of Lactococcus lactis IL1403
Impact of invertase overexpression on cell size, starch granule formation and cell wall properties during tuber development in potatoes with modified carbon allocation patterns
Antisense inhibition of plastidial phosphoglucomutase provides compelling evidence that potato tuber amyloplasts import carbon from the cytosol in the form of glucose-6-phosphate
Potato plants exhibiting combined antisense repression of cytosolic and plastidial isoforms of phosphoglucomutase surprisingly approximate wild type with respect to the rate of starch synthesis
Antisense repression of cytosolic phosphoglucomutase in potato (Solanum tuberosum) results in severe growth retardation, reduction in tuber number and altered carbon metabolism
Potato plants exhibiting combined antisense repression of cytosolic and plastidial isoforms of phosphoglucomutase surprsingly approximate wild type with respect to the rate of starch synthesis
Crystal Structures of N Acetylmannosamine Kinase Provide Insights into Enzyme Activity and Inhibition
Sialic acids are essential components of membrane glycoconjugates. They are responsible for the interaction, structure, and functionality of all deuterostome cells and have major functions in cellular processes in health and diseases. The key enzyme of the biosynthesis of sialic acid is the bifunctional UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase that transforms UDP-N-acetylglucosamine to N-acetylmannosamine (ManNAc) followed by its phosphorylation to ManNAc 6-phosphate and has a direct impact on the sialylation of cell surface components. Here, we present the crystal structures of the human N-acetylmannosamine kinase (MNK) domain of UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase in complexes with ManNAc at 1.64 Å resolution, MNK·ManNAc·ADP (1.82 Å) and MNK·ManNAc 6-phosphate·ADP (2.10 Å). Our findings offer detailed insights in the active center of MNK and serve as a structural basis to design inhibitors. We synthesized a novel inhibitor, 6-O-acetyl-ManNAc, which is more potent than those previously tested. Specific inhibitors of sialic acid biosynthesis may serve to further study biological functions of sialic acid