Structural basis for activation of glutaminase

Abstract

Glutaminase is a rate-limiting enzyme in glutaminolysis, which produces glutamate from glutamine and enters the TCA cycle[1]. In addition, it plays a key role in redox homeostasis[2], autophagy[3], immune system regulation[4], central nervous system maintenance[5], and senolysis[6]. Therefore, the allosteric regulation of glutaminase is a fascinating topic that has broad implications for our understanding of glutamine metabolism and related diseases[7-9]. Phosphate was discovered as a natural agonist for glutaminase in 1947[10], but the structural basis and mechanism for this regulation remains unclear. Using cryo-electron microscopy, here we determine the structure of human glutaminase with phosphate. This structure allows us to capture phosphate binding at the dimer-dimer interface at near atomic resolution, revealing an allosteric activation mechanism by remodelling the catalytic pocket. Surprisingly, we find that phosphate antagonizes BPTES (a classical antagonist) and CB-839 (the current subject of several phase II clinical trials). Accurate identification of phosphate binding sites lays the foundation for the design of glutaminase agonists and antagonists with broad pharmaceutical significance.