Abstract
Capillary electrophoresis mass spectrometry (CE/MS) was applied for the comprehensive survey of changes in amounts of metabolites upon the shift from photoautotrophic- to photomixotrophic conditions in Synechocystis sp. PCC 6803. When glucose was added in the light, the drastic change in metabolic processes, i.e., up-regulation of the oxidative pentose phosphate pathway and glycolysis together with down-regulation of the Calvin cycle, was observed in the wild-type cells. These responses seem prerequisite for the coordination between anabolic and catabolic reactions under photomixotrophic conditions. CE/MS analysis of pmgA-disrupted mutant which cannot grow under photomixotrophic conditions suggested that CO2 fixation rate was higher in the mutant than in the wild-type cells upon the addition of glucose. Concomitantly, 1) decrease in ATP and NADPH contents, 2) failure in activation of the oxidative pentose phosphate pathway and of respiratory electron transport and 3) aberrant accumulation of isocitrate were observed in the mutant under photomixotrophic conditions.
