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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

Thangavelu, K ; Pan, Catherine Qiurong ; Karlberg, Tobias LU ; Balaji, Ganapathy ; Uttamchandani, Mahesh ; Suresh, Valiyaveettil ; Schüler, Herwig LU orcid ; Low, Boon Chuan and Sivaraman, J (2012) In Proceedings of the National Academy of Sciences of the United States of America 109(20). p.10-7705
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,... (More)

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.

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publishing date
type
Contribution to journal
publication status
published
keywords
Allosteric Regulation/physiology, Cell Line, Tumor, Cell Proliferation/drug effects, Crystallography, Glutaminase/chemistry, Humans, Kidney/enzymology, MAP Kinase Kinase 1/metabolism, MAP Kinase Kinase 2/genetics, MAP Kinase Signaling System/physiology, Models, Molecular, Mutation/genetics, Phosphorylation, Protein Binding, Protein Conformation, Proto-Oncogene Proteins c-raf/genetics, Signal Transduction/physiology, Sulfides/metabolism, Thiadiazoles/metabolism
in
Proceedings of the National Academy of Sciences of the United States of America
volume
109
issue
20
pages
6 pages
publisher
National Academy of Sciences
external identifiers
  • pmid:22538822
  • scopus:84861209572
ISSN
1091-6490
DOI
10.1073/pnas.1116573109
language
English
LU publication?
no
id
c98b6b21-9757-45c6-a9fb-b6c2feb31771
date added to LUP
2024-11-21 17:58:12
date last changed
2025-05-23 19:58:04
@article{c98b6b21-9757-45c6-a9fb-b6c2feb31771,
  abstract     = {{<p>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.</p>}},
  author       = {{Thangavelu, K and Pan, Catherine Qiurong and Karlberg, Tobias and Balaji, Ganapathy and Uttamchandani, Mahesh and Suresh, Valiyaveettil and Schüler, Herwig and Low, Boon Chuan and Sivaraman, J}},
  issn         = {{1091-6490}},
  keywords     = {{Allosteric Regulation/physiology; Cell Line, Tumor; Cell Proliferation/drug effects; Crystallography; Glutaminase/chemistry; Humans; Kidney/enzymology; MAP Kinase Kinase 1/metabolism; MAP Kinase Kinase 2/genetics; MAP Kinase Signaling System/physiology; Models, Molecular; Mutation/genetics; Phosphorylation; Protein Binding; Protein Conformation; Proto-Oncogene Proteins c-raf/genetics; Signal Transduction/physiology; Sulfides/metabolism; Thiadiazoles/metabolism}},
  language     = {{eng}},
  month        = {{05}},
  number       = {{20}},
  pages        = {{10--7705}},
  publisher    = {{National Academy of Sciences}},
  series       = {{Proceedings of the National Academy of Sciences of the United States of America}},
  title        = {{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}},
  url          = {{http://dx.doi.org/10.1073/pnas.1116573109}},
  doi          = {{10.1073/pnas.1116573109}},
  volume       = {{109}},
  year         = {{2012}},
}