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Mealka M, Sierra NA, Avellaneda Matteo D, Albekioni E, Khoury R, Mai T, Conley BM, Coleman NJ, Sabo KA, Komives EA, Bobkov AA, Cooksy AL, Silletti S, Schiffer JM, Huxford T, Sohl CD. Active site remodeling in tumor-relevant IDH1 mutants drives distinct kinetic features and potential resistance mechanisms. Nat Commun 2024; 15:3785. [PMID: 38710674 PMCID: PMC11074275 DOI: 10.1038/s41467-024-48277-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 04/26/2024] [Indexed: 05/08/2024] Open
Abstract
Mutations in human isocitrate dehydrogenase 1 (IDH1) drive tumor formation in a variety of cancers by replacing its conventional activity with a neomorphic activity that generates an oncometabolite. Little is understood of the mechanistic differences among tumor-driving IDH1 mutants. We previously reported that the R132Q mutant unusually preserves conventional activity while catalyzing robust oncometabolite production, allowing an opportunity to compare these reaction mechanisms within a single active site. Here, we employ static and dynamic structural methods and observe that, compared to R132H, the R132Q active site adopts a conformation primed for catalysis with optimized substrate binding and hydride transfer to drive improved conventional and neomorphic activity over R132H. This active site remodeling reveals a possible mechanism of resistance to selective mutant IDH1 therapeutic inhibitors. This work enhances our understanding of fundamental IDH1 mechanisms while pinpointing regions for improving inhibitor selectivity.
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Affiliation(s)
- Matthew Mealka
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Nicole A Sierra
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | | | - Elene Albekioni
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Rachel Khoury
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Timothy Mai
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Brittany M Conley
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Nalani J Coleman
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Kaitlyn A Sabo
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Elizabeth A Komives
- Department of Chemistry & Biochemistry, University of California San Diego, La Jolla, CA, USA
| | - Andrey A Bobkov
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Andrew L Cooksy
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Steve Silletti
- Department of Chemistry & Biochemistry, University of California San Diego, La Jolla, CA, USA
| | | | - Tom Huxford
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Christal D Sohl
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA.
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Mealka M, Sierra NA, Matteo DA, Albekioni E, Khoury R, Mai T, Conley BM, Coleman NJ, Sabo KA, Komives EA, Bobkov AA, Cooksy AL, Silletti S, Schiffer JM, Huxford T, Sohl CD. Active site remodeling in tumor-relevant IDH1 mutants drives distinct kinetic features and potential resistance mechanisms. RESEARCH SQUARE 2024:rs.3.rs-3889456. [PMID: 38464189 PMCID: PMC10925425 DOI: 10.21203/rs.3.rs-3889456/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Mutations in human isocitrate dehydrogenase 1 (IDH1) drive tumor formation in a variety of cancers by replacing its conventional activity with a neomorphic activity that generates an oncometabolite. Little is understood of the mechanistic differences among tumor-driving IDH1 mutants. We previously reported that the R132Q mutant uniquely preserves conventional activity while catalyzing robust oncometabolite production, allowing an opportunity to compare these reaction mechanisms within a single active site. Here, we employed static and dynamic structural methods and found that, compared to R132H, the R132Q active site adopted a conformation primed for catalysis with optimized substrate binding and hydride transfer to drive improved conventional and neomorphic activity over R132H. This active site remodeling revealed a possible mechanism of resistance to selective mutant IDH1 therapeutic inhibitors. This work enhances our understanding of fundamental IDH1 mechanisms while pinpointing regions for improving inhibitor selectivity.
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Affiliation(s)
- Matthew Mealka
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Nicole A. Sierra
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | | | - Elene Albekioni
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Rachel Khoury
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Timothy Mai
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Brittany M. Conley
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Nalani J. Coleman
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Kaitlyn A. Sabo
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Elizabeth A. Komives
- Department of Chemistry & Biochemistry, University of California San Diego, La Jolla, CA, USA
| | - Andrey A. Bobkov
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA USA
| | - Andrew L. Cooksy
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Steve Silletti
- Department of Chemistry & Biochemistry, University of California San Diego, La Jolla, CA, USA
| | | | - Tom Huxford
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Christal D. Sohl
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
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Mealka M, Sierra NA, Matteo DA, Albekioni E, Khoury R, Mai T, Conley BM, Coleman NJ, Sabo KA, Komives EA, Bobkov AA, Cooksy AL, Silletti S, Schiffer JM, Huxford T, Sohl CD. Active site remodeling in tumor-relevant IDH1 mutants drives distinct kinetic features and potential resistance mechanisms. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.10.574970. [PMID: 38260668 PMCID: PMC10802581 DOI: 10.1101/2024.01.10.574970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Mutations in human isocitrate dehydrogenase 1 (IDH1) drive tumor formation in a variety of cancers by replacing its conventional activity with a neomorphic activity that generates an oncometabolite. Little is understood of the mechanistic differences among tumor-driving IDH1 mutants. We previously reported that the R132Q mutant uniquely preserves conventional activity while catalyzing robust oncometabolite production, allowing an opportunity to compare these reaction mechanisms within a single active site. Here, we employed static and dynamic structural methods and found that, compared to R132H, the R132Q active site adopted a conformation primed for catalysis with optimized substrate binding and hydride transfer to drive improved conventional and neomorphic activity over R132H. This active site remodeling revealed a possible mechanism of resistance to selective mutant IDH1 therapeutic inhibitors. This work enhances our understanding of fundamental IDH1 mechanisms while pinpointing regions for improving inhibitor selectivity.
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Affiliation(s)
- Matthew Mealka
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Nicole A. Sierra
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | | | - Elene Albekioni
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Rachel Khoury
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Timothy Mai
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Brittany M. Conley
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Nalani J. Coleman
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Kaitlyn A. Sabo
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Elizabeth A. Komives
- Department of Chemistry & Biochemistry, University of California San Diego, La Jolla, CA, USA
| | - Andrey A. Bobkov
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA USA
| | - Andrew L. Cooksy
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Steve Silletti
- Department of Chemistry & Biochemistry, University of California San Diego, La Jolla, CA, USA
| | | | - Tom Huxford
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
| | - Christal D. Sohl
- Department of Chemistry & Biochemistry, San Diego State University, San Diego, CA, USA
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Sabo KA, Albekioni E, Caliger D, Coleman NJ, Thornberg E, Avellaneda Matteo D, Komives EA, Silletti S, Sohl CD. Capturing the Dynamic Conformational Changes of Human Isocitrate Dehydrogenase 1 (IDH1) upon Ligand and Metal Binding Using Hydrogen-Deuterium Exchange Mass Spectrometry. Biochemistry 2023; 62:1145-1159. [PMID: 36854124 PMCID: PMC10089636 DOI: 10.1021/acs.biochem.2c00636] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
Human isocitrate dehydrogenase 1 (IDH1) is a highly conserved metabolic enzyme that catalyzes the interconversion of isocitrate and α-ketoglutarate. Kinetic and structural studies with IDH1 have revealed evidence of striking conformational changes that occur upon binding of its substrates, isocitrate and NADP+, and its catalytic metal cation. Here, we used hydrogen-deuterium exchange mass spectrometry (HDX-MS) to build a comprehensive map of the dynamic conformational changes experienced by IDH1 upon ligand binding. IDH1 proved well-suited for HDX-MS analysis, allowing us to capture profound changes in solvent accessibility at substrate binding sites and at a known regulatory region, as well as at more distant local subdomains that appear to support closure of this protein into its active conformation. HDX-MS analysis suggested that IDH1 is primarily purified with NADP(H) bound in the absence of its metal cation. Subsequent metal cation binding, even in the absence of isocitrate, was critical for driving large conformational changes. WT IDH1 folded into its fully closed conformation only when the full complement of substrates and metal was present. Finally, we show evidence supporting a previously hypothesized partially open conformation that forms prior to the catalytically active state, and we propose this conformation is driven by isocitrate binding in the absence of metal.
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Affiliation(s)
- Kaitlyn A Sabo
- San Diego State University, Department of Chemistry and Biochemistry, San Diego, California 92182, United States
| | - Elene Albekioni
- San Diego State University, Department of Chemistry and Biochemistry, San Diego, California 92182, United States
| | - Danielle Caliger
- San Diego State University, Department of Chemistry and Biochemistry, San Diego, California 92182, United States
| | - Nalani J Coleman
- San Diego State University, Department of Chemistry and Biochemistry, San Diego, California 92182, United States
| | - Ella Thornberg
- San Diego State University, Department of Chemistry and Biochemistry, San Diego, California 92182, United States
| | - Diego Avellaneda Matteo
- San Diego State University, Department of Chemistry and Biochemistry, San Diego, California 92182, United States
| | - Elizabeth A Komives
- University of California, San Diego, Department of Chemistry and Biochemistry, La Jolla, California 92093, United States
| | - Steve Silletti
- University of California, San Diego, Department of Chemistry and Biochemistry, La Jolla, California 92093, United States
| | - Christal D Sohl
- San Diego State University, Department of Chemistry and Biochemistry, San Diego, California 92182, United States
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An acidic residue buried in the dimer interface of isocitrate dehydrogenase 1 (IDH1) helps regulate catalysis and pH sensitivity. Biochem J 2021; 477:2999-3018. [PMID: 32729927 DOI: 10.1042/bcj20200311] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 07/28/2020] [Accepted: 07/29/2020] [Indexed: 12/19/2022]
Abstract
Isocitrate dehydrogenase 1 (IDH1) catalyzes the reversible NADP+-dependent conversion of isocitrate to α-ketoglutarate (αKG) to provide critical cytosolic substrates and drive NADPH-dependent reactions like lipid biosynthesis and glutathione regeneration. In biochemical studies, the forward reaction is studied at neutral pH, while the reverse reaction is typically characterized in more acidic buffers. This led us to question whether IDH1 catalysis is pH-regulated, which would have functional implications under conditions that alter cellular pH, like apoptosis, hypoxia, cancer, and neurodegenerative diseases. Here, we show evidence of catalytic regulation of IDH1 by pH, identifying a trend of increasing kcat values for αKG production upon increasing pH in the buffers we tested. To understand the molecular determinants of IDH1 pH sensitivity, we used the pHinder algorithm to identify buried ionizable residues predicted to have shifted pKa values. Such residues can serve as pH sensors, with changes in protonation states leading to conformational changes that regulate catalysis. We identified an acidic residue buried at the IDH1 dimer interface, D273, with a predicted pKa value upshifted into the physiological range. D273 point mutations had decreased catalytic efficiency and, importantly, loss of pH-regulated catalysis. Based on these findings, we conclude that IDH1 activity is regulated, at least in part, by pH. We show this regulation is mediated by at least one buried acidic residue ∼12 Å from the IDH1 active site. By establishing mechanisms of regulation of this well-conserved enzyme, we highlight catalytic features that may be susceptible to pH changes caused by cell stress and disease.
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