Phosphofructokinase in glycolysis: Bridging enzymology and cell biology

ATP-dependent phosphofructokinase (PFK) catalyzes a key committed step in glycolysis. Also called the "gatekeeper" of glycolysis, PFKs catalyze an irreversible phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate. While eukaryotic PFKs are more than double the size of prokaryotic PFKs, the overall structure and mechanism of PFKs are largely conserved from prokaryotes to eukaryotes. Usually tetrameric to be active, PFKs are also found to form higher-order structures, such as octamers in yeasts and multimeric filaments in mammals. Due to their central role in glycolysis, the enzymatic activity of PFKs is highly regulated by a myriad of allosteric effectors, post-translational modifications, and various signaling pathways. Such complex regulatory networks of PFKs often result from and/or result in a variety of protein-protein interactions, thus providing the molecular basis of dynamic association and dissociation of PFKs into multienzyme metabolic assemblies (i.e., metabolons) in cells. The concept of metabolon has now become an organizational principle for a cell to regulate the function of PFKs and thus govern glycolysis. Therefore, this article aims to integrate current knowledge in PFK enzymology and cell biology to provide a molecular and cellular framework for repositioning this century-old drug target for innovative therapeutic applications.