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Abstract
RNA recognition frequently results in conformational changes that optimize intermolecular binding. As a consequence, the overall binding affinity of RNA to its binding partners depends not only on the intermolecular interactions formed in the bound state but also on the energy cost associated with changing the RNA conformational distribution. Measuring these "conformational penalties" is, however, challenging because bound RNA conformations tend to have equilibrium populations in the absence of the binding partner that fall outside detection by conventional biophysical methods. In this study we employ as a model system HIV-1 TAR RNA and its interaction with the ligand argininamide (ARG), a mimic of TAR's cognate protein binding partner, the transactivator Tat. We use NMR chemical shift perturbations and relaxation dispersion in combination with Bayesian inference to develop a detailed thermodynamic model of coupled conformational change and ligand binding. Starting from a comprehensive 12-state model of the equilibrium, we estimate the energies of six distinct detectable thermodynamic states that are not accessible by currently available methods. Our approach identifies a minimum of four RNA intermediates that differ in terms of the TAR conformation and ARG occupancy. The dominant bound TAR conformation features two bound ARG ligands and has an equilibrium population in the absence of ARG that is below detection limit. Consequently, even though ARG binds to TAR with an apparent overall weak affinity (Kdapp ≈ 0.2 mM), it binds the prefolded conformation with a Kd in the nM range. Our results show that conformational penalties can be major determinants of RNA-ligand binding affinity as well as a source of binding cooperativity, with important implications for a predictive understanding of how RNA is recognized and for RNA-targeted drug discovery.
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Affiliation(s)
- Nicole I. Orlovsky
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, United States
| | - Hashim M. Al-Hashimi
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, United States
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
| | - Terrence G. Oas
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, United States
- Department of Chemistry, Duke University, Durham, North Carolina 27708, United States
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Maurizy C, Quinternet M, Abel Y, Verheggen C, Santo PE, Bourguet M, C F Paiva A, Bragantini B, Chagot ME, Robert MC, Abeza C, Fabre P, Fort P, Vandermoere F, M F Sousa P, Rain JC, Charpentier B, Cianférani S, Bandeiras TM, Pradet-Balade B, Manival X, Bertrand E. The RPAP3-Cterminal domain identifies R2TP-like quaternary chaperones. Nat Commun 2018; 9:2093. [PMID: 29844425 PMCID: PMC5974087 DOI: 10.1038/s41467-018-04431-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Accepted: 04/19/2018] [Indexed: 12/22/2022] Open
Abstract
R2TP is an HSP90 co-chaperone that assembles important macro-molecular machineries. It is composed of an RPAP3-PIH1D1 heterodimer, which binds the two essential AAA+ATPases RUVBL1/RUVBL2. Here, we resolve the structure of the conserved C-terminal domain of RPAP3, and we show that it directly binds RUVBL1/RUVBL2 hexamers. The human genome encodes two other proteins bearing RPAP3-C-terminal-like domains and three containing PIH-like domains. Systematic interaction analyses show that one RPAP3-like protein, SPAG1, binds PIH1D2 and RUVBL1/2 to form an R2TP-like complex termed R2SP. This co-chaperone is enriched in testis and among 68 of the potential clients identified, some are expressed in testis and others are ubiquitous. One substrate is liprin-α2, which organizes large signaling complexes. Remarkably, R2SP is required for liprin-α2 expression and for the assembly of liprin-α2 complexes, indicating that R2SP functions in quaternary protein folding. Effects are stronger at 32 °C, suggesting that R2SP could help compensating the lower temperate of testis. R2TP is an HSP90 co-chaperone composed of an RPAP3-PIH1D1 heterodimer, which binds two essential AAA+ ATPases RUVBL1/RUVBL2. Here authors use a structural approach to study RPAP3 and find an RPAP3-like protein (SPAG1) which also forms a co-chaperone complex with PIH1D2 and RUVBL1/2 enriched in testis.
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Affiliation(s)
- Chloé Maurizy
- IGMM, CNRS, Université de Montpellier, Montpellier, 34293, France.,Equipe labélisée Ligue Nationale Contre le Cancer, 34293, Montpellier, France
| | - Marc Quinternet
- CNRS, INSERM, IBSLOR, Université de Lorraine, Nancy, F-54000, France
| | - Yoann Abel
- IGMM, CNRS, Université de Montpellier, Montpellier, 34293, France.,Equipe labélisée Ligue Nationale Contre le Cancer, 34293, Montpellier, France
| | - Céline Verheggen
- IGMM, CNRS, Université de Montpellier, Montpellier, 34293, France.,Equipe labélisée Ligue Nationale Contre le Cancer, 34293, Montpellier, France
| | - Paulo E Santo
- iBET, Instituto de Biologia Experimental e Tecnológica, Apartado 12, Oeiras, 2781-901, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, Oeiras, 2780-157, Portugal
| | - Maxime Bourguet
- Laboratoire de Spectrométrie de Masse BioOrganique, Université de Strasbourg, CNRS, IPHC UMR 7178, Strasbourg, 67000, France
| | - Ana C F Paiva
- iBET, Instituto de Biologia Experimental e Tecnológica, Apartado 12, Oeiras, 2781-901, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, Oeiras, 2780-157, Portugal
| | | | | | - Marie-Cécile Robert
- IGMM, CNRS, Université de Montpellier, Montpellier, 34293, France.,Equipe labélisée Ligue Nationale Contre le Cancer, 34293, Montpellier, France
| | - Claire Abeza
- IGMM, CNRS, Université de Montpellier, Montpellier, 34293, France.,Equipe labélisée Ligue Nationale Contre le Cancer, 34293, Montpellier, France
| | - Philippe Fabre
- CNRS, IMoPA, Université de Lorraine, Nancy, F-54000, France
| | - Philippe Fort
- CRBM, University of Montpellier, CNRS, 1919 Route de Mende, Montpellier, 34090, France
| | | | - Pedro M F Sousa
- iBET, Instituto de Biologia Experimental e Tecnológica, Apartado 12, Oeiras, 2781-901, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, Oeiras, 2780-157, Portugal
| | | | | | - Sarah Cianférani
- Laboratoire de Spectrométrie de Masse BioOrganique, Université de Strasbourg, CNRS, IPHC UMR 7178, Strasbourg, 67000, France
| | - Tiago M Bandeiras
- iBET, Instituto de Biologia Experimental e Tecnológica, Apartado 12, Oeiras, 2781-901, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, Oeiras, 2780-157, Portugal
| | | | - Xavier Manival
- CNRS, IMoPA, Université de Lorraine, Nancy, F-54000, France.
| | - Edouard Bertrand
- IGMM, CNRS, Université de Montpellier, Montpellier, 34293, France. .,Equipe labélisée Ligue Nationale Contre le Cancer, 34293, Montpellier, France.
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Williamson MP. Using chemical shift perturbation to characterise ligand binding. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2013; 73:1-16. [PMID: 23962882 DOI: 10.1016/j.pnmrs.2013.02.001] [Citation(s) in RCA: 968] [Impact Index Per Article: 88.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 02/12/2013] [Accepted: 02/18/2013] [Indexed: 05/05/2023]
Abstract
Chemical shift perturbation (CSP, chemical shift mapping or complexation-induced changes in chemical shift, CIS) follows changes in the chemical shifts of a protein when a ligand is added, and uses these to determine the location of the binding site, the affinity of the ligand, and/or possibly the structure of the complex. A key factor in determining the appearance of spectra during a titration is the exchange rate between free and bound, or more specifically the off-rate koff. When koff is greater than the chemical shift difference between free and bound, which typically equates to an affinity Kd weaker than about 3μM, then exchange is fast on the chemical shift timescale. Under these circumstances, the observed shift is the population-weighted average of free and bound, which allows Kd to be determined from measurement of peak positions, provided the measurements are made appropriately. (1)H shifts are influenced to a large extent by through-space interactions, whereas (13)Cα and (13)Cβ shifts are influenced more by through-bond effects. (15)N and (13)C' shifts are influenced both by through-bond and by through-space (hydrogen bonding) interactions. For determining the location of a bound ligand on the basis of shift change, the most appropriate method is therefore usually to measure (15)N HSQC spectra, calculate the geometrical distance moved by the peak, weighting (15)N shifts by a factor of about 0.14 compared to (1)H shifts, and select those residues for which the weighted shift change is larger than the standard deviation of the shift for all residues. Other methods are discussed, in particular the measurement of (13)CH3 signals. Slow to intermediate exchange rates lead to line broadening, and make Kd values very difficult to obtain. There is no good way to distinguish changes in chemical shift due to direct binding of the ligand from changes in chemical shift due to allosteric change. Ligand binding at multiple sites can often be characterised, by simultaneous fitting of many measured shift changes, or more simply by adding substoichiometric amounts of ligand. The chemical shift changes can be used as restraints for docking ligand onto protein. By use of quantitative calculations of ligand-induced chemical shift changes, it is becoming possible to determine not just the position but also the orientation of ligands.
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Affiliation(s)
- Mike P Williamson
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
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