Two phosphoenolpyruvate carboxykinases with differing biochemical properties in Chlamydomonas reinhardtii

• Published in: FEBS letters 2023-02, Vol.597 (4), p.585-597
• Main Authors: Torresi, Florencia, Rodriguez, Fernanda M., Gomez‐Casati, Diego F., Martín, Mariana
• Format: Article
• Language: English
• Subjects: algal PEPCK; Chlamydomonas reinhardtii; Chlamydomonas reinhardtii - genetics; Citrates; PEPCK; Phenylalanine; Phosphoenolpyruvate; phosphoenolpyruvate carboxykinase; Phosphoenolpyruvate Carboxykinase (ATP) - genetics; Protein Isoforms
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1002/1873-3468.14590

Phosphoenolpyruvate carboxykinase (PEPCK) catalyses the reversible reaction of decarboxylation and phosphorylation of oxaloacetate (OAA) to generate phosphoenolpyruvate (PEP) and CO2 playing mainly a gluconeogenic role in green algae. We found two PEPCK isoforms in Chlamydomonas reinhardtii and we cloned, purified and characterised both enzymes. ChlrePEPCK1 is more active as decarboxylase than ChlrePEPCK2. ChlrePEPCK1 is hexameric and its activity is affected by citrate, phenylalanine and malate, while ChlrePEPCK2 is monomeric and it is regulated by citrate, phenylalanine and glutamine. We postulate that the two PEPCK isoforms found originate from alternative splicing of the gene or regulated proteolysis of the enzyme. The presence of these two isoforms would be part of a mechanism to finely regulate the biological activity of PEPCKs. Chlamydomonas reinhardtii contains two phosphoenolpyruvate carboxykinase (PEPCK) isoforms that are formed by alternative splicing or proteolysis of the N‐terminal region. Both proteins differ in their oligomerisation, kinetics and regulation by metabolites. The presence of two proteins with different properties would be a mechanism to regulate PEPCK localisation in algae and their function in carbon metabolism.