Mitochondrial localization and structure-based phosphate activation mechanism of Glutaminase C with implications for cancer metabolism

Author(s)

Cassago, Alexandre ^[1] ; Ferreira, Amanda P. S. ^[1] ; Ferreira, Igor M. ^[1] ; Fornezari, Camila ^[1] ; Gomes, Emerson R. M. ^[1] ; Greene, Kai Su ^[2] ; Pereira, Humberto M. ^[3] ; Garratt, Richard C. ^[3] ; Dias, Sandra M. G. ^[1] ; Ambrosio, Andre L. B. ^[1]

Affiliation

^[1] Ctr Nacl Pesquisa Energia & Mat, Lab Nacl Biociencias, BR-13083970 Campinas, SP - Brazil

^[2] Cornell Univ, Dept Mol Med, Coll Vet Med, Ithaca, NY 14853 - USA

^[3] Univ Sao Paulo, Ctr Biotecnol Mol Estrutural, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA; v. 109, n. 4, p. 1092-1097, JAN 24 2012.
• Web of Science Citations: 102

Abstract

Glutamine is an essential nutrient for cancer cell proliferation, especially in the context of citric acid cycle anaplerosis. In this manuscript we present results that collectively demonstrate that, of the three major mammalian glutaminases identified to date, the lesser studied splice variant of the gene gls, known as Glutaminase C (GAC), is important for tumor metabolism. We show that, although levels of both the kidney-type isoforms are elevated in tumor vs. normal tissues, GAC is distinctly mitochondrial. GAC is also most responsive to the activator inorganic phosphate, the content of which is supposedly higher in mitochondria subject to hypoxia. Analysis of X-ray crystal structures of GAC in different bound states suggests a mechanism that introduces the tetramerization-induced lifting of a ``gating loop{''} as essential for the phosphate-dependent activation process. Surprisingly, phosphate binds inside the catalytic pocket rather than at the oligomerization interface. Phosphate also mediates substrate entry by competing with glutamate. A greater tendency to oligomerize differentiates GAC from its alternatively spliced isoform and the cycling of phosphate in and out of the active site distinguishes it from the liver-type isozyme, which is known to be less dependent on this ion. (AU)

• FAPESP's process: 10/05003-0 - Structural and functional studies of key proteins underlying the metabolic adaptation process in tumors
• Grantee: Andre Luis Berteli Ambrosio
• Support Opportunities: Regular Research Grants
• FAPESP's process: 09/10875-9 - Cellular and biochemical studies of the glutaminase enzyme and its relation with cancer
• Grantee: Sandra Martha Gomes Dias
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 10/05987-0 - Structural determination of the kidney type glutaminase and the search for its binding partners.
• Grantee: Alexandre Cassago
• Support Opportunities: Scholarships in Brazil - Post-Doctoral