3VP1

Crystal structure of human glutaminase in complex with L-glutamate and BPTES

Summary for 3VP1

• Entry DOI: 10.2210/pdb3vp1/pdb
• Descriptor: Glutaminase kidney isoform, mitochondrial, N,N'-[sulfanediylbis(ethane-2,1-diyl-1,3,4-thiadiazole-5,2-diyl)]bis(2-phenylacetamide), GLUTAMIC ACID, ... (5 entities in total)
• Functional Keywords: hydrolase-hydrolase inhibitor complex, hydrolase/hydrolase inhibitor
• Biological source: Homo sapiens (human)
• Cellular location: Isoform 1: Cytoplasm, cytosol. Isoform 3: Mitochondrion: O94925
• Total number of polymer chains: 1
• Total formula weight: 35552.55

Authors

Thangavelu, K.,Sivaraman, J. (deposition date: 2012-02-23, release date: 2012-06-13, Last modification date: 2023-11-08)

Primary citation

Thangavelu, K.,Pan, C.Q.,Karlberg, T.,Balaji, G.,Uttamchandani, M.,Suresh, V.,Schuler, H.,Low, B.C.,Sivaraman, J.
Structural basis for the allosteric inhibitory mechanism of human kidney-type glutaminase (KGA) and its regulation by Raf-Mek-Erk signaling in cancer cell metabolism.
Proc.Natl.Acad.Sci.USA, 109:7705-7710, 2012

PubMed Abstract: Besides thriving on altered glucose metabolism, cancer cells undergo glutaminolysis to meet their energy demands. As the first enzyme in catalyzing glutaminolysis, human kidney-type glutaminase isoform (KGA) is becoming an attractive target for small molecules such as BPTES [bis-2-(5 phenylacetamido-1, 2, 4-thiadiazol-2-yl) ethyl sulfide], although the regulatory mechanism of KGA remains unknown. On the basis of crystal structures, we reveal that BPTES binds to an allosteric pocket at the dimer interface of KGA, triggering a dramatic conformational change of the key loop (Glu312-Pro329) near the catalytic site and rendering it inactive. The binding mode of BPTES on the hydrophobic pocket explains its specificity to KGA. Interestingly, KGA activity in cells is stimulated by EGF, and KGA associates with all three kinase components of the Raf-1/Mek2/Erk signaling module. However, the enhanced activity is abrogated by kinase-dead, dominant negative mutants of Raf-1 (Raf-1-K375M) and Mek2 (Mek2-K101A), protein phosphatase PP2A, and Mek-inhibitor U0126, indicative of phosphorylation-dependent regulation. Furthermore, treating cells that coexpressed Mek2-K101A and KGA with suboptimal level of BPTES leads to synergistic inhibition on cell proliferation. Consequently, mutating the crucial hydrophobic residues at this key loop abrogates KGA activity and cell proliferation, despite the binding of constitutive active Mek2-S222/226D. These studies therefore offer insights into (i) allosteric inhibition of KGA by BPTES, revealing the dynamic nature of KGA's active and inhibitory sites, and (ii) cross-talk and regulation of KGA activities by EGF-mediated Raf-Mek-Erk signaling. These findings will help in the design of better inhibitors and strategies for the treatment of cancers addicted with glutamine metabolism.

PubMed: 22538822
DOI: 10.1073/pnas.1116573109

Experimental method

X-RAY DIFFRACTION (2.3 Å)