Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:6.4.1.1 (pyruvate carboxylase)
 1,516 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A rapid fractionation method for determination of metabolite levels in the chloroplast and the extrachloroplast compartment of Chlamydomonas reinhardtii has been developed. Protoplasts containing one large chloroplast were fractionated by passing them through a multilayer gradient containing digitonin, polyacrylamide, and a mixture of silicone oil and bromodecane. Lysis of the plasma membrane and the separation of the chloroplasts from most of the extrachloroplast material was achieved within less than 5 s. The chloroplast enriched fraction was contaminated with 3% fumarase (mitochondria) and 13% phosphoenol pyruvate carboxylase (cytosol). Metabolites of the upper glycolytic chain were detected mainly in the chloroplasts, whereas 2-phosphoglycerate was found only in the extrachloroplast compartment. Analysis of changes in metabolite concentrations after transition to anaerobic conditions in the dark pointed to a regulation of carbohydrate catabolism by chloroplast phosphofructokinase and by cytosolic pyruvatekinase.
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PMID:Compartmented metabolite pools in protoplasts from the green alga Chlamydomonas reinhardtii: changes after transition from aerobiosis to anaerobiosis in the dark. 182 18

The green alga Chlamydomonas reinhardtii has a network of fermentation pathways that become active when cells acclimate to anoxia. Hydrogenase activity is an important component of this metabolism, and we have compared metabolic and regulatory responses that accompany anaerobiosis in wild-type C. reinhardtii cells and a null mutant strain for the HYDEF gene (hydEF-1 mutant), which encodes an [FeFe] hydrogenase maturation protein. This mutant has no hydrogenase activity and exhibits elevated accumulation of succinate and diminished production of CO2 relative to the parental strain during dark, anaerobic metabolism. In the absence of hydrogenase activity, increased succinate accumulation suggests that the cells activate alternative pathways for pyruvate metabolism, which contribute to NAD(P)H reoxidation, and continued glycolysis and fermentation in the absence of O2. Fermentative succinate production potentially proceeds via the formation of malate, and increases in the abundance of mRNAs encoding two malate-forming enzymes, pyruvate carboxylase and malic enzyme, are observed in the mutant relative to the parental strain following transfer of cells from oxic to anoxic conditions. Although C. reinhardtii has a single gene encoding pyruvate carboxylase, it has six genes encoding putative malic enzymes. Only one of the malic enzyme genes, MME4, shows a dramatic increase in expression (mRNA abundance) in the hydEF-1 mutant during anaerobiosis. Furthermore, there are marked increases in transcripts encoding fumarase and fumarate reductase, enzymes putatively required to convert malate to succinate. These results illustrate the marked metabolic flexibility of C. reinhardtii and contribute to the development of an informed model of anaerobic metabolism in this and potentially other algae.
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PMID:Flexibility in anaerobic metabolism as revealed in a mutant of Chlamydomonas reinhardtii lacking hydrogenase activity. 1911 46