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Karamanos TK, Matthews S. Biomolecular NMR in the AI-assisted structural biology era: Old tricks and new opportunities. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2024; 1872:140949. [PMID: 37572958 DOI: 10.1016/j.bbapap.2023.140949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 08/07/2023] [Accepted: 08/09/2023] [Indexed: 08/14/2023]
Abstract
Over the last 40 years nuclear magnetic resonance (NMR) spectroscopy has established itself as one of the most versatile techniques for the characterization of biomolecules, especially proteins. Given the molecular size limitations of NMR together with recent advances in cryo-electron microscopy and artificial intelligence-assisted protein structure prediction, the bright future of NMR in structural biology has been put into question. In this mini review we argue the contrary. We discuss the unique opportunities solution NMR offers to the protein chemist that distinguish it from all other experimental or computational methods, and how it can benefit from machine learning.
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Affiliation(s)
| | - Stephen Matthews
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London.
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Abstract
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Thanks to recent
improvements in NMR spectrometer hardware and
pulse sequence design, modern 13C NMR has become a useful
tool for biomolecular applications. The complete assignment of a protein
can be accomplished by using 13C detected multinuclear
experiments and it can provide unique information relevant for the
study of a variety of different biomolecules including paramagnetic
proteins and intrinsically disordered proteins. A wide range of NMR
observables can be measured, concurring to the structural and dynamic
characterization of a protein in isolation, as part of a larger complex,
or even inside a living cell. We present the different properties
of 13C with respect to 1H, which provide the
rationale for the experiments developed and their application, the
technical aspects that need to be faced, and the many experimental
variants designed to address different cases. Application areas where
these experiments successfully complement proton NMR are also described.
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Affiliation(s)
- Isabella C Felli
- Department of Chemistry "Ugo Schiff" and Magnetic Resonance Center, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino (Florence), Italy
| | - Roberta Pierattelli
- Department of Chemistry "Ugo Schiff" and Magnetic Resonance Center, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino (Florence), Italy
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Barnes CA, Starich MR, Tjandra N, Mishra P. Simultaneous measurement of 1H C/N-R 2's for rapid acquisition of backbone and sidechain paramagnetic relaxation enhancements (PREs) in proteins. JOURNAL OF BIOMOLECULAR NMR 2021; 75:109-118. [PMID: 33625630 PMCID: PMC8096723 DOI: 10.1007/s10858-021-00359-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 02/02/2021] [Indexed: 06/12/2023]
Abstract
Paramagnetic relaxation enhancements (PREs) are routinely used to provide long-range distance restraints for the determination of protein structures, to resolve protein dynamics, ligand-protein binding sites, and lowly populated species, using Nuclear Magnetic Resonance Spectroscopy (NMR). Here, we propose a simultaneous 1H-15 N, 1H-13C SESAME based pulse scheme for the rapid acquisition of 1HC/N-R2 relaxation rates for the determination of backbone and sidechain PREs of proteins. The 1HN-R2 rates from the traditional and our approach on Ubiquitin (UBQ) are well correlated (R2 = 0.99), revealing their potential to be used quantitatively. Comparison of the S57C UBQ calculated and experimental PREs provided backbone and side chain Q factors of 0.23 and 0.24, respectively, well-fitted to the UBQ NMR structure, showing that our approach can be used to acquire accurate PRE rates from the functionally important sites of proteins but in at least half the time as traditional methods.
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Affiliation(s)
- C Ashley Barnes
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Mary R Starich
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Nico Tjandra
- Biochemistry and Biophysics Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Pushpa Mishra
- Department of Biophysics, University of Mumbai, Maharashtra, Mumbai, 400098, India.
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Pritchard RB, Hansen DF. Characterising side chains in large proteins by protonless 13C-detected NMR spectroscopy. Nat Commun 2019; 10:1747. [PMID: 30988305 PMCID: PMC6465260 DOI: 10.1038/s41467-019-09743-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 03/28/2019] [Indexed: 11/24/2022] Open
Abstract
Side chains cover protein surfaces and are fundamental to processes as diverse as substrate recognition, protein folding and enzyme catalysis. However, characterisation of side-chain motions has so far been restricted to small proteins and methyl-bearing side chains. Here we present a class of methods, based on 13C-detected NMR spectroscopy, to more generally quantify motions and interactions of side chains in medium-to-large proteins. A single, uniformly isotopically labelled sample is sufficient to characterise the side chains of six different amino acid types. Side-chain conformational dynamics on the millisecond time-scale can be quantified by incorporating chemical exchange saturation transfer (CEST) into the presented methods, whilst long-range 13C-13C scalar couplings reporting on nanosecond to millisecond motions can be quantified in proteins as large as 80 kDa. The presented class of methods promises characterisation of side-chain behaviour at a level that has so far been reserved for the protein backbone. Analysis of side-chain motions by NMR has so far been restricted to small proteins and methyl-bearing side chains. Here, the authors present NMR methods based on 13C direct detection of highly deuterated protein samples that yield sharp and well-resolved signals and allow the characterisation of side-chain conformational dynamics of six different amino acid types in medium-to-large proteins.
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Affiliation(s)
- Ruth B Pritchard
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, UK, WC1E 6BT
| | - D Flemming Hansen
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, UK, WC1E 6BT.
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Mackenzie HW, Hansen DF. Arginine Side-Chain Hydrogen Exchange: Quantifying Arginine Side-Chain Interactions in Solution. Chemphyschem 2019; 20:252-259. [PMID: 30085401 PMCID: PMC6391956 DOI: 10.1002/cphc.201800598] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Indexed: 02/03/2023]
Abstract
The rate with which labile backbone hydrogen atoms in proteins exchange with the solvent has long been used to probe protein interactions in aqueous solutions. Arginine, an essential amino acid found in many interaction interfaces, is capable of an impressive range of interactions via its guanidinium group. The hydrogen exchange rate of the guanidinium hydrogens therefore becomes an important measure to quantify side-chain interactions. Herein we present an NMR method to quantify the hydrogen exchange rates of arginine side-chain 1 Hϵ protons and thus present a method to gauge the strength of arginine side-chain interactions. The method employs 13 C-detection and the one-bond deuterium isotope shift observed for 15 Nϵ to generate two exchanging species in 1 H2 O/2 H2 O mixtures. An application to the protein T4 Lysozyme is shown, where protection factors calculated from the obtained exchange rates correlate well with the interactions observed in the crystal structure. The methodology presented provides an important step towards characterising interactions of arginine side-chains in enzymes, in phase separation, and in protein interaction interfaces in general.
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Affiliation(s)
- Harold W. Mackenzie
- Institute of Structural and Molecular Biology Division of BiosciencesUniversity College LondonLondon WC1E 6BTUnited Kingdom
| | - D. Flemming Hansen
- Institute of Structural and Molecular Biology Division of BiosciencesUniversity College LondonLondon WC1E 6BTUnited Kingdom
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6
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Brockerman JA, Okon M, Withers SG, McIntosh LP. The pK a values of the catalytic residues in the retaining glycoside hydrolase T26H mutant of T4 lysozyme. Protein Sci 2018; 28:620-632. [PMID: 30537432 DOI: 10.1002/pro.3562] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 11/29/2018] [Accepted: 12/03/2018] [Indexed: 12/24/2022]
Abstract
T4 phage lysozyme (T4L) is an enzyme that cleaves bacterial cell wall peptidoglycan. Remarkably, the single substitution of the active site Thr26 to a His (T26H) converts T4L from an inverting to a retaining glycoside hydrolase with transglycosylase activity. It has been proposed that T26H-T4L follows a double displacement mechanism with His26 serving as a nucleophile to form a covalent glycosyl-enzyme intermediate (Kuroki et al., PNAS 1999; 96:8949-8954). To gain further insights into this or alternative mechanisms, we used NMR spectroscopy to measure the acid dissociation constants (pKa values) and/or define the ionization states of the Asp, Glu, His, and Arg residues in the T4L mutant. Most notably, the pKa value of the putative nucleophile His26 is 6.8 ± 0.1, whereas that of the general acid Glu11 is 4.7 ± 0.1. If the proposed mechanism holds true, then T26H-T4L follows a reverse protonation pathway in which only a minor population of the free enzyme is in its catalytically competent ionization state with His26 deprotonated and Glu11 protonated. Our studies also confirm that all arginines in T26H-T4L, including the active site Arg145, are positively charged under neutral pH conditions. BRIEF STATEMENT: The replacement of a single amino acid changes T4 lysozyme from an inverting to a retaining glycoside hydrolase. Using NMR spectroscopy, we measured the pKa values of the ionizable residues in the active site of this mutant enzyme. Along with previously reported data, these results provide important constraints for understanding the catalytic mechanisms by which the wild-type and mutant form of T4 lysozyme cleave bacterial peptidoglycan.
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Affiliation(s)
- Jacob A Brockerman
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Mark Okon
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada.,Department of Chemistry, University of British Columbia, Vancouver, British Columbia, V6T 1Z1, Canada
| | - Stephen G Withers
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada.,Department of Chemistry, University of British Columbia, Vancouver, British Columbia, V6T 1Z1, Canada.,Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada
| | - Lawrence P McIntosh
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada.,Department of Chemistry, University of British Columbia, Vancouver, British Columbia, V6T 1Z1, Canada.,Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada
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Abstract
The phenomenon of chemical or conformational exchange in NMR spectroscopy has enabled detailed characterization of time-dependent aspects of biomolecular function, including folding, molecular recognition, allostery, and catalysis, on timescales from microsecond to second. Importantly, NMR methods based on a variety of spin relaxation parameters have been developed that provide quantitative information on interconversion kinetics, thermodynamic properties, and structural features of molecular states populated to a fraction of a percent at equilibrium and otherwise unobservable by other NMR approaches. The ongoing development of more sophisticated experimental techniques and the necessity to apply these methods to larger and more complex molecular systems engenders a corresponding need for theoretical advances describing such techniques and facilitating data analysis in applications. This review surveys current aspects of the theory of chemical exchange, as utilized in ZZ-exchange; Hahn and Carr-Purcell-Meiboom-Gill (CPMG) spin-echo; and R1ρ, chemical exchange saturation transfer (CEST), and dark state saturation transfer (DEST) spin-locking experiments. The review emphasizes theoretical results for kinetic topologies with more than two interconverting states, both to obtain compact analytical forms suitable for data analysis and to establish conditions for distinguishability between alternative kinetic schemes.
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Affiliation(s)
- Arthur G Palmer
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, United States.
| | - Hans Koss
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, United States
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