PYRUVATE-KINASE ISOZYMES - ANCIENT DIVERSITY RETAINED IN MODERN PLANT-CELLS

Pyruvate kinase is a key regulatory enzyme of glycolysis. Phylogenetic analyses of the sequences coding for pyruvate kinase from plants and other organisms revealed unexpected diversity of this glycolytic enzym e in the progenitor of the present-day eukaryotes. Plants contain an a ncient lineage of cytosolic pyruvate kinase, which may have diverged f rom the animal pyruvate kinase genes prior to the plant-animal diverge nce. The plant cytosolic pyruvate kinase genes are no more closely rel ated to the animal and fungal pyruvate kinase genes than to the prokar yotic pyruvate kinase genes. The results suggest that the plant pyruva te kinase genes and the animal-fungal pyruvate kinase genes have desce nded from divergent isozymes which existed in the progenitor of the pr esent-day eukaryotes and prokaryotes.