The function of glycine decarboxylase complex is optimized to maintain high photorespiratory flux via buffering of its reaction products.
Oxidation of glycine in photorespiratory pathway is the major flux through mitochondria of C3 plants in the light. It sustains increased intramitochondrial concentrations of NADH and NADPH, which are required to engage the internal rotenone-insensitive NAD(P)H dehydrogenases and the alternative oxidase. We discuss here possible mechanisms of high photorespiratory flux maintenance in mitochondria and suggest that it is fulfilled under conditions where the concentrations of glycine decarboxylase reaction products NADH and CO2 achieve an equilibrium provided by malate dehydrogenase and carbonic anhydrase, respectively. This results in the removal of these products from the glycine decarboxylase multienzyme active sites and in the maintenance of their concentrations at levels sufficiently low to prevent substrate inhibition of the reaction.
Cereal Research Centre, Agriculture and Agri-Food Canada, Winnipeg, MB, R3T 2M9, Canada.
Natalia V
NV
Bykova
Department of Molecular Biology and Genetics, Aarhus University, DK-4200 Slagelse, Denmark.
Ian M
IM
Møller
Department of Plant Physiology, Umeå Plant Science Centre, University of Umeå, S-901 87 Umeå, Sweden.
Per
P
Gardeström
Department of Biology, Memorial University of Newfoundland, St. John's, NL, A1B 3X9, Canada. Electronic address: igamberdiev@mun.ca.
Abir U
AU
Igamberdiev
D002245:Carbon Dioxide / Q000378:metabolism; D002256:Carbonic Anhydrases / Q000378:metabolism; D050959:Glycine Decarboxylase Complex / Q000378:metabolism*; D008291:Malate Dehydrogenase / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D009243:NAD / Q000378:metabolism; D010944:Plants / Q000201:enzymology* / Q000378:metabolism*
D009243:NAD; D002245:Carbon Dioxide; D008291:Malate Dehydrogenase; D050959:Glycine Decarboxylase Complex; D002256:Carbonic Anhydrases
Carbonic anhydrase; Glycine decarboxylase; Malate dehydrogenase; Non-coupled electron transport; Photorespiration