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Pressure, motion, and conformational entropy in molecular recognition by proteins. BIOPHYSICAL REPORTS 2022; 3:100098. [PMID: 36647534 PMCID: PMC9840116 DOI: 10.1016/j.bpr.2022.100098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022]
Abstract
The thermodynamics of molecular recognition by proteins is a central determinant of complex biochemistry. For over a half-century, detailed cryogenic structures have provided deep insight into the energetic contributions to ligand binding by proteins. More recently, a dynamical proxy based on NMR-relaxation methods has revealed an unexpected richness in the contributions of conformational entropy to the thermodynamics of ligand binding. Here, we report the pressure dependence of fast internal motion within the ribonuclease barnase and its complex with the protein barstar. In what we believe is a first example, we find that protein dynamics are conserved along the pressure-binding thermodynamic cycle. The femtomolar affinity of the barnase-barstar complex exists despite a penalty by -TΔSconf of +11.7 kJ/mol at ambient pressure. At high pressure, however, the overall change in side-chain dynamics is zero, and binding occurs with no conformational entropy penalty, suggesting an important role of conformational dynamics in the adaptation of protein function to extreme environments. Distinctive clustering of the pressure sensitivity is observed in response to both pressure and binding, indicating the presence of conformational heterogeneity involving less efficiently packed alternative conformation(s). The structural segregation of dynamics observed in barnase is striking and shows how changes in both the magnitude and the sign of regional contributions of conformational entropy to the thermodynamics of protein function are possible.
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2
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Chikunova A, Ubbink M. The roles of highly conserved, non‐catalytic residues in class A β‐lactamases. Protein Sci 2022; 31:e4328. [PMID: 35634774 PMCID: PMC9112487 DOI: 10.1002/pro.4328] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/03/2022] [Accepted: 04/20/2022] [Indexed: 11/12/2022]
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3
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Yin G, Lv G, Zhang J, Jiang H, Lai T, Yang Y, Ren Y, Wang J, Yi C, Chen H, Huang Y, Xiao C. Early-stage structure-based drug discovery for small GTPases by NMR spectroscopy. Pharmacol Ther 2022; 236:108110. [PMID: 35007659 DOI: 10.1016/j.pharmthera.2022.108110] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 01/04/2022] [Accepted: 01/05/2022] [Indexed: 12/13/2022]
Abstract
Small GTPase or Ras superfamily, including Ras, Rho, Rab, Ran and Arf, are fundamental in regulating a wide range of cellular processes such as growth, differentiation, migration and apoptosis. They share structural and functional similarities for binding guanine nucleotides and hydrolyzing GTP. Dysregulations of Ras proteins are involved in the pathophysiology of multiple human diseases, however there is still a stringent need for effective treatments targeting these proteins. For decades, small GTPases were recognized as 'undruggable' targets due to their complex regulatory mechanisms and lack of deep pockets for ligand binding. NMR has been critical in deciphering the structural and dynamic properties of the switch regions that are underpinning molecular switch functions of small GTPases, which pave the way for developing new effective inhibitors. The recent progress of drug or lead molecule development made for small GTPases profoundly delineated how modern NMR techniques reshape the field of drug discovery. In this review, we will summarize the progress of structural and dynamic studies of small GTPases, the NMR techniques developed for structure-based drug screening and their applications in early-stage drug discovery for small GTPases.
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Affiliation(s)
- Guowei Yin
- The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen 518107, China.
| | - Guohua Lv
- Division of Histology & Embryology, Medical College, Jinan University, Guangzhou 511486, Guangdong, China
| | - Jerry Zhang
- University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC 27516, USA
| | - Hongmei Jiang
- The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen 518107, China
| | - Tianqi Lai
- Division of Histology & Embryology, Medical College, Jinan University, Guangzhou 511486, Guangdong, China
| | - Yushan Yang
- The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen 518107, China
| | - Yong Ren
- The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen 518107, China
| | - Jing Wang
- College of Life Sciences, Northwest University, Xi'an 710069, Shaanxi, China
| | - Chenju Yi
- The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen 518107, China
| | - Hao Chen
- Key Laboratory of Biomedical Information Engineering of Ministry of Education, Biomedical Informatics & Genomics Center, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi Province 710049, PR China; Research Institute of Xi'an Jiaotong University, Zhejiang, Hangzhou, Zhejiang Province 311215, PR China
| | - Yun Huang
- Howard Hughes Medical Institute, Chevy Chase 20815, MD, USA; Department of Physiology & Biophysics, Weill Cornell Medicine, New York 10065, NY, USA.
| | - Chaoni Xiao
- College of Life Sciences, Northwest University, Xi'an 710069, Shaanxi, China.
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Sapienza PJ, Popov KI, Mowrey DD, Falk BT, Dokholyan NV, Lee AL. Inter-Active Site Communication Mediated by the Dimer Interface β-Sheet in the Half-the-Sites Enzyme, Thymidylate Synthase. Biochemistry 2019; 58:3302-3313. [PMID: 31283187 DOI: 10.1021/acs.biochem.9b00486] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thymidylate synthase (TS) is a dimeric enzyme conserved in all life forms that exhibits the allosteric feature of half-the-sites activity. Neither the reason for nor the mechanism of this phenomenon is understood. We used a combined nuclear magnetic resonance (NMR) and molecular dynamics approach to study a stable intermediate preceding hydride transfer, which is the rate-limiting and half-the-sites step. In NMR titrations with ligands leading to this intermediate, we measured chemical shifts of the apoenzyme (lig0), the saturated holoenzyme (lig2), and the typically elusive singly bound (lig1) states. Approximately 40 amides showed quartet patterns providing direct NMR evidence of coupling between the active site and probes >30 Å away in the distal subunit. Quartet peak patterns have symmetrical character, indicating reciprocity in communicating the first and second binding events to the distal protomer. Quartets include key catalytic residues and map to the dimer interface β-sheet, which also represents the shortest path between the two active sites. Simulations corroborate the coupling observed in solution in that there is excellent overlap between quartet residues and main-chain atoms having intersubunit cross-correlated motions. Simulations identify five hot spot residues, three of which lie at the kink in the unique β-bulge abutting the active sites on either end of the sheet. Interstrand cross-correlated motions become more organized and pronounced as the enzyme progresses from lig0 to lig1 and ultimately lig2. Coupling in the apparently symmetrical complex has implications for half-the-sites reactivity and potentially resolves the paradox of inequivalent TS active sites despite the vast majority of X-ray structures appearing to be symmetrical.
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Affiliation(s)
- Paul J Sapienza
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-7355 , United States
| | - Konstantin I Popov
- Department of Biochemistry and Biophysics, School of Medicine , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - David D Mowrey
- Department of Biochemistry and Biophysics, School of Medicine , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Bradley T Falk
- Department of Biochemistry and Biophysics, School of Medicine , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
| | - Nikolay V Dokholyan
- Department of Pharmacology and Department of Biochemistry and Molecular Biology , Penn State College of Medicine , Hershey , Pennsylvania 17033 , United States.,Department of Chemistry and Department of Biomedical Engineering , The Pennsylvania State University , University Park , Pennsylvania 16801 , United States
| | - Andrew L Lee
- Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-7355 , United States.,Department of Biochemistry and Biophysics, School of Medicine , The University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599 , United States
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5
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Allostery and dynamics in small G proteins. Biochem Soc Trans 2018; 46:1333-1343. [PMID: 30301845 DOI: 10.1042/bst20170569] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 08/31/2018] [Accepted: 09/04/2018] [Indexed: 11/17/2022]
Abstract
The Ras family of small guanine nucleotide-binding proteins behave as molecular switches: they are switched off and inactive when bound to GDP but can be activated by GTP binding in response to signal transduction pathways. Early structural analysis showed that two regions of the protein, which change conformation depending on the nucleotide present, mediate this switch. A large number of X-ray, NMR and simulation studies have shown that this is an over-simplification. The switch regions themselves are highly dynamic and can exist in distinct sub-states in the GTP-bound form that have different affinities for other proteins. Furthermore, regions outside the switches have been found to be sensitive to the nucleotide state of the protein, indicating that allosteric change is more widespread than previously thought. Taken together, the accrued knowledge about small G protein structures, allostery and dynamics will be essential for the design and testing of the next generation of inhibitors, both orthosteric and allosteric, as well as for understanding their mode of action.
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Hines JP, Dent MR, Stevens DJ, Burstyn JN. Site-directed spin label electron paramagnetic resonance spectroscopy as a probe of conformational dynamics in the Fe(III) "locked-off" state of the CO-sensing transcription factor CooA. Protein Sci 2018; 27:1670-1679. [PMID: 30168206 PMCID: PMC6194275 DOI: 10.1002/pro.3449] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 05/25/2018] [Accepted: 05/29/2018] [Indexed: 01/30/2023]
Abstract
The transcriptional activator CooA belongs to the CRP/FNR (cAMP receptor protein/fumarate and nitrate reductase) superfamily of transcriptional regulators and uses heme to sense carbon monoxide (CO). Effector-driven allosteric activation is well understood in CRP, a CooA homologue. A structural allosteric activation model for CooA exists which parallels that of CRP; however, the role of protein dynamics, which is crucial in CRP, is not well understood in CooA. We employed site-directed spin labeling electron paramagnetic resonance spectroscopy to probe CooA motions on the μs-ms timescale. We created a series of Cys substitution variants, each with a cysteine residue introduced into a key functional region of the protein: K26C, E60C, F132C, D134C, and S175C. The heme environment and DNA binding affinity of each variant were comparable to those of wild-type CooA, with the exception of F132C, which displayed reduced DNA binding affinity. This observation confirms a previously hypothesized role for Phe132 in transmitting the allosteric CO binding signal. Osmolyte perturbation studies of Fe(III) "locked-off" CooA variants labeled with either MTSL or MAL-6 nitroxide spin labels revealed that multicomponent EPR spectra report on conformational flexibility on the μs-ms timescale. Multiple dynamic populations exist at every site examined in the structurally uncharacterized Fe(III) "locked-off" CooA. This observation suggests that, in direct contrast to effector-free CRP, Fe(III) "locked-off" CooA undergoes conformational exchange on the μs-ms timescale. Importantly, we establish MAL-6 as a spin label with a redox-stable linkage that may be utilized to compare conformational dynamics between functional states of CooA.
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Affiliation(s)
- Judy P. Hines
- Department of ChemistryUniversity of Wisconsin–MadisonMadisonWisconsin
| | - Matthew R. Dent
- Department of ChemistryUniversity of Wisconsin–MadisonMadisonWisconsin
| | - Daniel J. Stevens
- Department of ChemistryUniversity of Wisconsin–MadisonMadisonWisconsin
| | - Judith N. Burstyn
- Department of ChemistryUniversity of Wisconsin–MadisonMadisonWisconsin
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Abstract
Molecular recognition by proteins is fundamental to molecular biology. Dissection of the thermodynamic energy terms governing protein-ligand interactions has proven difficult, with determination of entropic contributions being particularly elusive. NMR relaxation measurements have suggested that changes in protein conformational entropy can be quantitatively obtained through a dynamical proxy, but the generality of this relationship has not been shown. Twenty-eight protein-ligand complexes are used to show a quantitative relationship between measures of fast side-chain motion and the underlying conformational entropy. We find that the contribution of conformational entropy can range from favorable to unfavorable, which demonstrates the potential of this thermodynamic variable to modulate protein-ligand interactions. For about one-quarter of these complexes, the absence of conformational entropy would render the resulting affinity biologically meaningless. The dynamical proxy for conformational entropy or "entropy meter" also allows for refinement of the contributions of solvent entropy and the loss in rotational-translational entropy accompanying formation of high-affinity complexes. Furthermore, structure-based application of the approach can also provide insight into long-lived specific water-protein interactions that escape the generic treatments of solvent entropy based simply on changes in accessible surface area. These results provide a comprehensive and unified view of the general role of entropy in high-affinity molecular recognition by proteins.
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Boulton S, Melacini G. Advances in NMR Methods To Map Allosteric Sites: From Models to Translation. Chem Rev 2016; 116:6267-304. [PMID: 27111288 DOI: 10.1021/acs.chemrev.5b00718] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The last five years have witnessed major developments in the understanding of the allosteric phenomenon, broadly defined as coupling between remote molecular sites. Such advances have been driven not only by new theoretical models and pharmacological applications of allostery, but also by progress in the experimental approaches designed to map allosteric sites and transitions. Among these techniques, NMR spectroscopy has played a major role given its unique near-atomic resolution and sensitivity to the dynamics that underlie allosteric couplings. Here, we highlight recent progress in the NMR methods tailored to investigate allostery with the goal of offering an overview of which NMR approaches are best suited for which allosterically relevant questions. The picture of the allosteric "NMR toolbox" is provided starting from one of the simplest models of allostery (i.e., the four-state thermodynamic cycle) and continuing to more complex multistate mechanisms. We also review how such an "NMR toolbox" has assisted the elucidation of the allosteric molecular basis for disease-related mutations and the discovery of novel leads for allosteric drugs. From this overview, it is clear that NMR plays a central role not only in experimentally validating transformative theories of allostery, but also in tapping the full translational potential of allosteric systems.
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Affiliation(s)
- Stephen Boulton
- Department of Chemistry and Chemical Biology Department of Biochemistry and Biomedical Sciences, McMaster University , 1280 Main St. W., Hamilton L8S 4M1, Canada
| | - Giuseppe Melacini
- Department of Chemistry and Chemical Biology Department of Biochemistry and Biomedical Sciences, McMaster University , 1280 Main St. W., Hamilton L8S 4M1, Canada
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Liu Q, Shi C, Yu L, Zhang L, Xiong Y, Tian C. General order parameter based correlation analysis of protein backbone motions between experimental NMR relaxation measurements and molecular dynamics simulations. Biochem Biophys Res Commun 2015; 457:467-72. [PMID: 25600810 DOI: 10.1016/j.bbrc.2015.01.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 01/07/2015] [Indexed: 11/30/2022]
Abstract
Internal backbone dynamic motions are essential for different protein functions and occur on a wide range of time scales, from femtoseconds to seconds. Molecular dynamic (MD) simulations and nuclear magnetic resonance (NMR) spin relaxation measurements are valuable tools to gain access to fast (nanosecond) internal motions. However, there exist few reports on correlation analysis between MD and NMR relaxation data. Here, backbone relaxation measurements of (15)N-labeled SH3 (Src homology 3) domain proteins in aqueous buffer were used to generate general order parameters (S(2)) using a model-free approach. Simultaneously, 80 ns MD simulations of SH3 domain proteins in a defined hydrated box at neutral pH were conducted and the general order parameters (S(2)) were derived from the MD trajectory. Correlation analysis using the Gromos force field indicated that S(2) values from NMR relaxation measurements and MD simulations were significantly different. MD simulations were performed on models with different charge states for three histidine residues, and with different water models, which were SPC (simple point charge) water model and SPC/E (extended simple point charge) water model. S(2) parameters from MD simulations with charges for all three histidines and with the SPC/E water model correlated well with S(2) calculated from the experimental NMR relaxation measurements, in a site-specific manner.
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Affiliation(s)
- Qing Liu
- Hefei National Laboratory for Physical Sciences at The Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, PR China
| | - Chaowei Shi
- Hefei National Laboratory for Physical Sciences at The Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, PR China
| | - Lu Yu
- Hefei National Laboratory for Physical Sciences at The Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, PR China; High Magnetic Field Laboratory, Chinese Academy of Science, Hefei, Anhui, 230031, PR China
| | - Longhua Zhang
- Hefei National Laboratory for Physical Sciences at The Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, PR China
| | - Ying Xiong
- Hefei National Laboratory for Physical Sciences at The Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, PR China.
| | - Changlin Tian
- Hefei National Laboratory for Physical Sciences at The Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230026, PR China; High Magnetic Field Laboratory, Chinese Academy of Science, Hefei, Anhui, 230031, PR China.
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