Molecular mechanism of glutaminase activation through filamentation and the role of filaments in mitophagy protection

• Published in: Nature structural & molecular biology Vol. 30; no. 12; pp. 1902 - 1912
• Main Authors: Adamoski, Douglas, Dias, Marilia Meira, Quesñay, Jose Edwin Neciosup, Yang, Zhengyi, Zagoriy, Ievgeniia, Steyer, Anna M., Rodrigues, Camila Tanimoto, da Silva Bastos, Alliny Cristiny, da Silva, Bianca Novaes, Costa, Renna Karoline Eloi, de Abreu, Flávia Mayumi Odahara, Islam, Zeyaul, Cassago, Alexandre, van Heel, Marin Gerard, Consonni, Sílvio Roberto, Mattei, Simone, Mahamid, Julia, Portugal, Rodrigo Villares, Ambrosio, Andre Luis Berteli, Dias, Sandra Martha Gomes
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.12.2023; Nature Publishing Group
• Subjects: 631/45/173; 631/535/1258/1259; 631/535/1258/1260; 631/80/642/333; Allosteric properties; Biochemistry; Biological Microscopy; Biomedical and Life Sciences; Electron microscopy; Enzymes; Filamentation; Filaments; Glutaminase; Glutamine; Ion beams; Life Sciences; Membrane Biology; Mitochondria; Mitophagy; Molecular modelling; Morphology; Nucleophiles; Protein Structure
• ISSN: 1545-9993; 1545-9985; 1545-9985
• DOI: 10.1038/s41594-023-01118-0

Glutaminase (GLS), which deaminates glutamine to form glutamate, is a mitochondrial tetrameric protein complex. Although inorganic phosphate (Pi) is known to promote GLS filamentation and activation, the molecular basis of this mechanism is unknown. Here we aimed to determine the molecular mechanism of Pi-induced mouse GLS filamentation and its impact on mitochondrial physiology. Single-particle cryogenic electron microscopy revealed an allosteric mechanism in which Pi binding at the tetramer interface and the activation loop is coupled to direct nucleophile activation at the active site. The active conformation is prone to enzyme filamentation. Notably, human GLS filaments form inside tubulated mitochondria following glutamine withdrawal, as shown by in situ cryo-electron tomography of cells thinned by cryo-focused ion beam milling. Mitochondria with GLS filaments exhibit increased protection from mitophagy. We reveal roles of filamentous GLS in mitochondrial morphology and recycling. Glutaminase is a mitochondrial complex that deaminates glutamine to form glutamate. Here the authors investigate inorganic-phosphate-induced enzyme filamentation, revealing an allosteric mechanism and roles of filamentous glutaminase in mitochondrial morphology and recycling.