Phosphoenolpyruvate Carboxylase Identified as a Key Enzyme in Erythrocytic Plasmodium falciparum Carbon Metabolism

PLoS Pathogens

Achuthanunni Chokkathukalam¹  Graham H. Coombs¹  David G. Watson²  Janet Storm³  Sonal Sethia³  Sylke Müller⁴  Rainer Breitling⁵  Gavin J. Blackburn⁵ 

[1] University of Strathclyde, Glasgow, United Kingdom;Glasgow Polyomics, Wolfson Wohl Cancer Research Centre, University of Glasgow, Glasgow, United Kingdom;Institute of Infection, Immunity & Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom;Manchester Institute of Biotechnology, Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom;Strathclyde Institute of Pharmacy and Biomedical Sciences

关键词: Metabolic labeling;    Plasmodium;    Glucose metabolism;    Drug metabolism;    Parasitic diseases;    Enzyme metabolism;    Metabolites;    Mitochondria;   

DOI  :  10.1371/journal.ppat.1003876

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Phospoenolpyruvate carboxylase (PEPC) is absent from humans but encoded in the Plasmodium falciparum genome, suggesting that PEPC has a parasite-specific function. To investigate its importance in P. falciparum, we generated a pepc null mutant (D10Δpepc), which was only achievable when malate, a reduction product of oxaloacetate, was added to the growth medium. D10Δpepc had a severe growth defect in vitro, which was partially reversed by addition of malate or fumarate, suggesting that pepc may be essential in vivo. Targeted metabolomics using 13C-U-D-glucose and 13C-bicarbonate showed that the conversion of glycolytically-derived PEP into malate, fumarate, aspartate and citrate was abolished in D10Δpepc and that pentose phosphate pathway metabolites and glycerol 3-phosphate were present at increased levels. In contrast, metabolism of the carbon skeleton of 13C,15N-U-glutamine was similar in both parasite lines, although the flux was lower in D10Δpepc; it also confirmed the operation of a complete forward TCA cycle in the wild type parasite. Overall, these data confirm the CO2 fixing activity of PEPC and suggest that it provides metabolites essential for TCA cycle anaplerosis and the maintenance of cytosolic and mitochondrial redox balance. Moreover, these findings imply that PEPC may be an exploitable target for future drug discovery.

【 授权许可】

CC BY