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Coricello A, Nardone AJ, Lupia A, Gratteri C, Vos M, Chaptal V, Alcaro S, Zhu W, Takagi Y, Richards NGJ. Cryo-EM and Molecular Dynamics Simulations Reveal Hidden Conformational Dynamics Controlling Ammonia Transport in Human Asparagine Synthetase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.16.541009. [PMID: 37292727 PMCID: PMC10245805 DOI: 10.1101/2023.05.16.541009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
How motions in enzymes might be linked to catalytic function is of considerable general interest. Recent advances in X-ray crystallography and cryogenic electron microscopy offer the promise of elucidating functionally relevant motions in proteins that are not easily amenable to study by other biophysical methods. Here we use 3D variability analysis (3DVA) on cryo-EM maps for wild type (WT) human asparagine synthetase (ASNS) and the R142I ASNS variant to identify conformational changes in the Arg-142 side chain, which mediates the formation of a catalytically relevant intramolecular tunnel. Our 3DVA results for WT ASNS are consistent with independent molecular dynamics (MD) simulations on a model generated from the X-ray structure of human ASNS. Moreover, MD simulations of computational models for the ASNS/β-aspartyl-AMP/MgPPi and R142I/β-aspartyl-AMP/MgPPi ternary complexes, suggest that the structural integrity of the tunnel is impaired in the R142I variant when β-aspartyl-AMP is present in the synthetase active site. The kinetic properties of the R142I ASNS variant support the proposed function of Arg-142. These studies illustrate the power of cryo-EM to identify localized motions and dissect the conformational landscape of large proteins. When combined with MD simulations, 3DVA is a powerful approach to understanding how conformational dynamics might regulate function in multi-domain enzymes possessing multiple active sites.
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Affiliation(s)
- Adriana Coricello
- Dipartimento di Scienze della Salute, Università "Magna Græcia" di Catanzaro, 88100 Catanzaro, Italy
- Present address: Dipartimento di Scienze Biomolecolari, Università degli Studi di Urbino "Carlo Bo", 61029 Urbino, Italy
| | - Alanya J Nardone
- Department of Chemistry & Biochemistry, Florida State University, Tallahassee, FL 32306, USA
| | - Antonio Lupia
- Net4Science Academic Spin-Off, Università "Magna Græcia" di Catanzaro, 88100 Catanzaro, Italy
- Present address: Dipartimento di Scienze della vita e dell'ambiente, Università degli Studi di Cagliari, 09042 Cagliari, Italy
| | - Carmen Gratteri
- Dipartimento di Scienze della Salute, Università "Magna Græcia" di Catanzaro, 88100 Catanzaro, Italy
| | - Matthijn Vos
- NanoImaging Core Facility, Centre de Resources et Recherches Technologiques, Institut Pasteur, 75015 Paris, France
| | - Vincent Chaptal
- Molecular Microbiology and Structural Biochemistry Laboratory, CNRS UMR 5086, University of Lyon, 69367 Lyon, France
| | - Stefano Alcaro
- Dipartimento di Scienze della Salute, Università "Magna Græcia" di Catanzaro, 88100 Catanzaro, Italy
- Net4Science Academic Spin-Off, Università "Magna Græcia" di Catanzaro, 88100 Catanzaro, Italy
| | - Wen Zhu
- Department of Chemistry & Biochemistry, Florida State University, Tallahassee, FL 32306, USA
| | - Yuichiro Takagi
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Nigel G J Richards
- School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, UK
- Foundation for Applied Molecular Evolution, Alachua, FL 32615, USA
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Ohler A, Taylor PE, Bledsoe JA, Iavarone AT, Gilbert NC, Offenbacher AR. Identification of the Thermal Activation Network in Human 15-Lipoxygenase-2: Divergence from Plant Orthologs and Its Relationship to Hydrogen Tunneling Activation Barriers. ACS Catal 2024; 14:5444-5457. [PMID: 38601784 PMCID: PMC11003420 DOI: 10.1021/acscatal.4c00439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 03/05/2024] [Accepted: 03/13/2024] [Indexed: 04/12/2024]
Abstract
The oxidation of polyunsaturated fatty acids by lipoxygenases (LOXs) is initiated by a C-H cleavage step in which the hydrogen atom is transferred quantum mechanically (i.e., via tunneling). In these reactions, protein thermal motions facilitate the conversion of ground-state enzyme-substrate complexes to tunneling-ready configurations and are thus important for transferring energy from the solvent to the active site for the activation of catalysis. In this report, we employed temperature-dependent hydrogen-deuterium exchange mass spectrometry (TDHDX-MS) to identify catalytically linked, thermally activated peptides in a representative animal LOX, human epithelial 15-LOX-2. TDHDX-MS of wild-type 15-LOX-2 was compared to two active site mutations that retain structural stability but have increased activation energies (Ea) of catalysis. The Ea value of one variant, V427L, is implicated to arise from suboptimal substrate positioning by increased active-site side chain rotamer dynamics, as determined by X-ray crystallography and ensemble refinement. The resolved thermal network from the comparative Eas of TDHDX-MS between wild-type and V426A is localized along the front face of the 15-LOX-2 catalytic domain. The network contains a clustering of isoleucine, leucine, and valine side chains within the helical peptides. This thermal network of 15-LOX-2 is different in location, area, and backbone structure compared to a model plant lipoxygenase from soybean that exhibits a low Ea value of catalysis compared to the human ortholog. The presented data provide insights into the divergence of thermally activated protein motions in plant and animal LOXs and their relationships to the enthalpic barriers for facilitating hydrogen tunneling.
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Affiliation(s)
- Amanda Ohler
- Department
of Chemistry, East Carolina University, Greenville, North Carolina 27858, United States
| | - Paris E. Taylor
- Department
of Biological Sciences, Louisiana State
University, Baton
Rouge, Louisiana 70803, United States
| | - Jasmine A. Bledsoe
- Department
of Biological Sciences, Louisiana State
University, Baton
Rouge, Louisiana 70803, United States
| | - Anthony T. Iavarone
- QB3/Chemistry
Mass Spectrometry Facility, University of
California, Berkeley, Berkeley, California 94720, United States
| | - Nathaniel C. Gilbert
- Department
of Biological Sciences, Louisiana State
University, Baton
Rouge, Louisiana 70803, United States
| | - Adam R. Offenbacher
- Department
of Chemistry, East Carolina University, Greenville, North Carolina 27858, United States
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Zaragoza JPT, Offenbacher AR, Hu S, Gee CL, Firestein ZM, Minnetian N, Deng Z, Fan F, Iavarone AT, Klinman JP. Temporal and spatial resolution of distal protein motions that activate hydrogen tunneling in soybean lipoxygenase. Proc Natl Acad Sci U S A 2023; 120:e2211630120. [PMID: 36867685 PMCID: PMC10013837 DOI: 10.1073/pnas.2211630120] [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: 07/06/2022] [Accepted: 01/27/2023] [Indexed: 03/05/2023] Open
Abstract
The enzyme soybean lipoxygenase (SLO) provides a prototype for deep tunneling mechanisms in hydrogen transfer catalysis. This work combines room temperature X-ray studies with extended hydrogen-deuterium exchange experiments to define a catalytically-linked, radiating cone of aliphatic side chains that connects an active site iron center of SLO to the protein-solvent interface. Employing eight variants of SLO that have been appended with a fluorescent probe at the identified surface loop, nanosecond fluorescence Stokes shifts have been measured. We report a remarkable identity of the energies of activation (Ea) for the Stokes shifts decay rates and the millisecond C-H bond cleavage step that is restricted to side chain mutants within an identified thermal network. These findings implicate a direct coupling of distal protein motions surrounding the exposed fluorescent probe to active site motions controlling catalysis. While the role of dynamics in enzyme function has been predominantly attributed to a distributed protein conformational landscape, the presented data implicate a thermally initiated, cooperative protein reorganization that occurs on a timescale faster than nanosecond and represents the enthalpic barrier to the reaction of SLO.
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Affiliation(s)
- Jan Paulo T. Zaragoza
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA94720
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
| | - Adam R. Offenbacher
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA94720
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
- Department of Chemistry, East Carolina University, Greenville, NC27858
| | - Shenshen Hu
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA94720
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
| | - Christine L. Gee
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA94720
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA94720
| | | | - Natalie Minnetian
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
| | - Zhenyu Deng
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
| | - Flora Fan
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
| | - Anthony T. Iavarone
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA94720
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
| | - Judith P. Klinman
- California Institute for Quantitative Biosciences, University of California Berkeley, Berkeley, CA94720
- Department of Chemistry, University of California Berkeley, Berkeley, CA94720
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA94720
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Högbom M. Nobel symposium #168 Visions of bio-inorganic chemistry: metals and the molecules of life. FEBS Lett 2023; 597:3-5. [PMID: 36623847 DOI: 10.1002/1873-3468.14559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Martin Högbom
- Department of Biochemistry and Biophysics, Stockholm University, Sweden
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