Regulation of isocitrate lyase inRhodobacter capsulatus E1F1
InRhodobacter capsulatus E1F1, isocitrate lyase (ICL) (EC 18.104.22.168) is a regulatory enzyme whose levels are increased in the presence of acetate as the sole carbon source. Acetate activated isocitrate lyase in a process dependent on energy supply and de novo protein synthesis. In contrast to isocitrate lyase, isocitrate dehydrogenase (ICDH) activity was independent of the carbon source used for growth and significantly increased in darkened cells. Pyruvate or yeast extract prevented in vivo activation of isocitrate lyase in cells growing on acetate. The enzyme was reversibly inactivated to a great extent in vitro by pyruvate and other oxoacids presumably involved in acetate metabolism. These results suggest that, inR. capsulatus E1F1, isocitrate lyase is regulated by both enzyme synthesis and oxoacid inactivation.
KeywordsEnzyme Acetate Carbon Source Protein Synthesis Pyruvate
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