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Kumar A, Satpati P. Divalent-Metal-Ion Selectivity of the CRISPR-Cas System-Associated Cas1 Protein: Insights from Classical Molecular Dynamics Simulations and Electronic Structure Calculations. J Phys Chem B 2021; 125:11943-11954. [PMID: 34694813 DOI: 10.1021/acs.jpcb.1c07744] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
CRISPR-associated protein 1 (Cas1) is a universally conserved essential metalloenzyme of the clustered regularly interspaced short palindromic repeat (CRISPR) immune system of prokaryotes (bacteria, archaea) that can cut and integrate a part of viral DNA to its host genome with the help of other proteins. The integrated DNA acts as a memory of viral infection, which can be transcribed to RNA and stop future infection by recognition (based on the RNA/DNA complementarity principle) followed by protein-mediated degradation of the viral DNA. It has been proposed that the presence of a single manganese (Mn2+) ion in a conserved divalent-metal-ion binding pocket (key residues: E190, H254, D265, D268) of Cas1 is crucial for its function. Cas1-mediated DNA degradation was proposed to be hindered by metal substitution, metal chelation, or mutation of the binding pocket residues. Cas1 is active toward dsDNA degradation with both Mn2+ and Mg2+. X-ray structures of Cas1 revealed an intricate atomic interaction network of the divalent-metal-ion binding pocket and opened up the possibility of modeling related metal ions (viz., Mg2+, Ca2+) in the binding pocket of wild-type (WT) and mutated Cas1 proteins for computational analysis, which includes (1) quantitative estimation of the energetics of the divalent-metal-ion preference and (2) exploring the structural and dynamical aspects of the protein in response to divalent-metal-ion substitution or amino acid mutation. Using the X-ray structure of the Cas1 protein from Pseudomonas aeruginosa as a template (PDB 3GOD), we performed (∼2.23 μs) classical molecular dynamics (MD) simulations to compare structural and dynamical differences between Mg2+- and Ca2+-bound binding pockets of wild-type (WT) and mutant (E190A, H254A, D265A, D268A) Cas1. Furthermore, reduced binding pocket models were generated from X-ray and molecular dynamics (MD) trajectories, and the resulting structures were subjected to quantum chemical calculations. Results suggest that Cas1 prefers Mg2+ binding relative to Ca2+ and the preference is the strongest for WT and the weakest for the D268A mutant. Quantum chemical calculations indicate that Mn2+ is the most preferred relative to both Mg2+ and Ca2+ in the wild-type and mutant Cas1. Substitution of Mg2+ by Ca2+ does not alter the interaction network between Cas1 and the divalent metal ion but increases the wetness of the binding pocket by introducing a single water molecule in the first coordination shell of the latter. The strength of metal-ion preference (Mg2+ versus Ca2+) seems to be dependent on the solvent accessibility of the divalent-metal-ion binding pocket, strongest for wild-type Cas1 (in which the metal-ion binding pocket is dry, which includes two water molecules) and the weakest for the D268A mutant (in which the metal-ion binding pocket is wet, which includes four water molecules).
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Affiliation(s)
- Abhishek Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Priyadarshi Satpati
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
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2
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Walker B, Jing Z, Ren P. Molecular dynamics free energy simulations of ATP:Mg 2+ and ADP:Mg 2+ using the polarizable force field AMOEBA. MOLECULAR SIMULATION 2021; 47:439-448. [PMID: 34421214 DOI: 10.1080/08927022.2020.1725003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
ATPases and GTPases are two important classes of protein that play critical roles in energy transduction, cellular signaling, gene regulation and catalysis. These proteins use cofactors such as nucleoside di and tri-phosphates (NTP, NDP) and can detect the difference between NDP and NTP which then induce different protein conformations. Mechanisms that drive proteins into the NTP or NDP conformation may depend on factors such as ligand structure and how Mg2+ coordinates with the ligand, amino acids in the pocket and water molecules. Here, we have used the advanced electrostatic and polarizable force field AMOEBA and molecular dynamics free energy simulations (MDFE) to examine the various binding mechanisms of ATP:Mg2+ and ADP:Mg2+.We compared the ATP:Mg2+ binding with previous studies using non-polarizable force fields and experimental data on the binding affinity. It was found that the total free energy of binding for ATP:Mg2+ (-7.00 ± 2.13 kcal/mol) is in good agreement with experimental values (-8.6 ± .2 kcal/mol)1. In addition, parameters for relevant protonation states of ATP, ADP, GTP and GDP have been derived. These parameters will allow for researchers to investigate biochemical phenomena involving NTP's and NDP's with greater accuracy than previous studies involving non-polarizable force fields.
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Affiliation(s)
- Brandon Walker
- Department of Biomedical Engineering at The University of Texas at Austin, Austin, Texas 78712, United States
| | - Zhifeng Jing
- Department of Biomedical Engineering at The University of Texas at Austin, Austin, Texas 78712, United States
| | - Pengyu Ren
- Department of Biomedical Engineering at The University of Texas at Austin, Austin, Texas 78712, United States
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3
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Kumar A, Satpati P. Why double-stranded RNA with 5'-monophosphate is a poor binder to retinoic acid-inducible gene-I with respect to 5'-hydroxyl analogue? J Biomol Struct Dyn 2020; 38:4048-4055. [PMID: 31543002 DOI: 10.1080/07391102.2019.1671225] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
AbbreviationsAActiveABNRAdopted basis Newton-RaphsonCARDsCaspase activation and recruitment domainsCTDC-terminal domaindsRNADouble-stranded RNAHEL1Helicase1HEL2Helicase2HEL2iHelicase2 insertionMDMolecular dynamicsNAInactivePPincerPDBprotein data bankPMEParticle mesh EwaldRIG-IRetinoic acid-inducible gene-IRMSDRoot mean square deviationRMSFRoot mean square fluctuationSDSteepest descentTIThermodynamic IntegrationCommunicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Amit Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - Priyadarshi Satpati
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
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4
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Mg 2+ vs Ca 2+ bound active site of group II intron- A MD study. J Mol Graph Model 2020; 97:107546. [PMID: 32018058 DOI: 10.1016/j.jmgm.2020.107546] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 11/25/2019] [Accepted: 01/21/2020] [Indexed: 11/20/2022]
Abstract
Group II introns are enzymes which undergo self-splicing and remove itself from pre-messenger RNA. X-ray structures of group II intron of Oceanobacillus iheyensis at various stages of the self-splicing pathway (pre-hydrolytic, post-hydrolytic, and ligand-free state) revealed intricate atomic interaction network in the active site of the intron. It has been confirmed that a heteronuclear metal ion cluster consisting of four metal ions (K1, K2 sites with K+ and M1, M2 sites with Mg2+) are crucial for function. Substitution of Mg2+ by Ca2+ results in loss of enzymatic activity. The X-ray structures not only opens up the possibility of modelling Mg2+ and Ca2+ bound active site of group II intron and quantitatively estimate the energetics of Mg2+ vs Ca2+ preference but also explore the relative structural and dynamical differences in response to divalent metal ion substitution. Thus, using X-ray structures as a template we performed molecular dynamics simulations to compare structural and dynamical differences between Mg2+ and Ca2+ bound active site of group II intron at various stages of the splicing pathway (i.e., pre-hydrolytic, post-hydrolytic, and ligand-free state). Quantitative estimation of Mg2+ vs Ca2+ selectivity at the M1, M2 sites confirmed Mg2+ preference at intron active sites relative to Ca2+. Ca2+ is relatively more hydrated in the intron active site relative to Mg2+. The local environment (bound nucleophilic water, interaction with scissile phosphate) around M2 is strikingly different between Mg2+ and Ca2+ bound pre-hydrolytic state. In the post-hydrolytic state, the exon part of the hydrolysis product is involved in direct interaction with the M1, whereas the intron part is highly flexible in our MD trajectories. Solvent exposure of M1, M2 sites are least in the pre-hydrolytic state, highest in the ligand-free state, and intermediate in the post-hydrolytic state.
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5
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Long MP, Alland S, Martin ME, Isborn CM. Molecular dynamics simulations of alkaline earth metal ions binding to DNA reveal ion size and hydration effects. Phys Chem Chem Phys 2020; 22:5584-5596. [DOI: 10.1039/c9cp06844a] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Classical molecular dynamics simulations reveal size-dependent trends of alkaline earth metal ions binding to DNA are due to ion size and hydration behavior.
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Affiliation(s)
| | - Serra Alland
- Department of Chemistry and Biochemistry
- University of Central Arkansas
- Arkansas 72035
- USA
| | - Madison E. Martin
- Department of Chemistry and Biochemistry
- University of Central Arkansas
- Arkansas 72035
- USA
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6
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Kumar A, Åqvist J, Satpati P. Principles of tRNA Ala Selection by Alanyl-tRNA Synthetase Based on the Critical G3·U70 Base Pair. ACS OMEGA 2019; 4:15539-15548. [PMID: 31572855 PMCID: PMC6761608 DOI: 10.1021/acsomega.9b01827] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 08/28/2019] [Indexed: 06/10/2023]
Abstract
Throughout evolution, the presence of a single G3·U70 mismatch in the acceptor stem of tRNAAla is the major determinant for aminoacylation with alanine by alanyl-tRNA synthetase (AlaRS). Recently reported crystal structures of the complexes AlaRS-tRNAAla/G3·U70 and AlaRS-tRNAAla/A3·U70 suggest two very different conformations, representing a reactive and a nonreactive state, respectively. On the basis of these structures, it has been proposed that the G3·U70 base pair guides the -CCA end of the tRNA acceptor stem into the active site of AlaRS, thereby enabling aminoacylation. The crystal structures open up the possibility of directly computing the energetics of tRNA specificity by AlaRS. We have carried out molecular dynamics free-energy simulations to quantitatively estimate tRNA discrimination by AlaRS, focusing on the mutations of the single critical base pair G3·U70 to uncover the energetics underlying the accuracy of tRNA selection. The calculations show that the reactive complex is highly selective in favor of the cognate tRNAAla/G3·U70 over its noncognate analogues (A3·U70/G3·C70/A3·C70). In contrast, the nonreactive complex is predicted to be unselective between tRNAAla/G3·U70 and tRNAAla/A3·U70. Utilizing our calculated relative binding free energies, we show how a simple three-step kinetic scheme for aminoacylation, involving both an initial nonspecific binding step and a subsequent transition to a selective reactive complex, accounts for the observed kinetics of the process.
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Affiliation(s)
- Amit Kumar
- Department
of Biosciences and Bioengineering, Indian
Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Johan Åqvist
- Department
of Cell and Molecular Biology, Uppsala University,
Biomedical Center, Box 596, Uppsala SE-751 24, Sweden
| | - Priyadarshi Satpati
- Department
of Biosciences and Bioengineering, Indian
Institute of Technology Guwahati, Guwahati 781039, Assam, India
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7
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Jing Z, Liu C, Cheng SY, Qi R, Walker BD, Piquemal JP, Ren P. Polarizable Force Fields for Biomolecular Simulations: Recent Advances and Applications. Annu Rev Biophys 2019; 48:371-394. [PMID: 30916997 DOI: 10.1146/annurev-biophys-070317-033349] [Citation(s) in RCA: 217] [Impact Index Per Article: 43.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Realistic modeling of biomolecular systems requires an accurate treatment of electrostatics, including electronic polarization. Due to recent advances in physical models, simulation algorithms, and computing hardware, biomolecular simulations with advanced force fields at biologically relevant timescales are becoming increasingly promising. These advancements have not only led to new biophysical insights but also afforded opportunities to advance our understanding of fundamental intermolecular forces. This article describes the recent advances and applications, as well as future directions, of polarizable force fields in biomolecular simulations.
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Affiliation(s)
- Zhifeng Jing
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA;
| | - Chengwen Liu
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA;
| | - Sara Y Cheng
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA;
| | - Rui Qi
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA;
| | - Brandon D Walker
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA;
| | - Jean-Philip Piquemal
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA; .,Sorbonne Université, CNRS, Laboratoire de Chimie Theórique, 75252 Paris CEDEX 05, France.,Institut Universitaire de France, 75005 Paris, France
| | - Pengyu Ren
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA;
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8
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Kumar A, Mukherjee D, Satpati P. Mutations in Parkinson's Disease Associated Protein DJ-1 Alter the Energetics of DJ-1 Dimerization. J Chem Inf Model 2019; 59:1497-1507. [PMID: 30789733 DOI: 10.1021/acs.jcim.8b00687] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Patients suffering from familial Parkinson's disease are linked to mutated DJ-1 protein. Wild-type DJ-1 occurs as a homodimer, which appears to be crucial for its function. It has been established that mutation (L166P) in DJ-1 protein could destabilize the DJ-1 homodimer. Hence, dimerization aspect of DJ-1 is fundamentally important for understanding its link to the disease. X-ray structures of wild-type DJ-1 dimer have given an atomic insight into the interaction network at the dimer interface. However, the energetics of dimerization in the wild-type and its mutant protein is unknown. Using the X-ray structure of wild-type DJ-1 as the template, we report ∼1.55 μs of molecular dynamics simulations to quantitatively estimate the relative free energy of DJ-1 dimerization in the disease linked variant (L166P, A104T, and M26I) with respect to its wild-type analogue. The results suggest that dimerization is disfavored for L166P and A104T mutations, severely for the former. Notably, the M26I mutation does not alter the energetics of DJ-1 dimerization. The dynamics of the DJ-1 dimer is significantly altered in response to the L166P and A104T mutations, resulting in the significant loss of interactions at the dimer interface. L166P mutant showed the structural difference and increased flexibility in α6, α7, α8 regions with respect to the WT. A structural difference in the α6 region was noticeable between WT and A104T mutant of DJ-1. The interaction network in the dimer interface is identical for the wild-type protein and the M26I mutant. No significant change in secondary structural content was observed for DJ-1 mutants (L166P, A104T, M26I) with respect to its WT analogue.
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Affiliation(s)
- Abhishek Kumar
- Department of Biosciences and Bioengineering , Indian Institute of Technology Guwahati , Guwahati , Assam 781039 , India
| | - Debaditya Mukherjee
- School of Bio Science & Technology (SBST) , VIT University , Vellore , Tamil Nadu 632014 , India
| | - Priyadarshi Satpati
- Department of Biosciences and Bioengineering , Indian Institute of Technology Guwahati , Guwahati , Assam 781039 , India
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9
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Abstract
PDZ domains contain 80-100 amino acids and bind short C-terminal sequences of target proteins. Their specificity is essential for cellular signaling pathways. We studied the binding of the Tiam1 PDZ domain to peptides derived from the C-termini of its Syndecan-1 and Caspr4 targets. We used free energy perturbation (FEP) to characterize the binding energetics of one wild-type and 17 mutant complexes by simulating 21 alchemical transformations between pairs of complexes. Thirteen complexes had known experimental affinities. FEP is a powerful tool to understand protein/ligand binding. It depends, however, on the accuracy of molecular dynamics force fields and conformational sampling. Both aspects require continued testing, especially for ionic mutations. For six mutations that did not modify the net charge, we obtained excellent agreement with experiment using the additive, AMBER ff99SB force field, with a root mean square deviation (RMSD) of 0.37 kcal/mol. For six ionic mutations that modified the net charge, agreement was also good, with one large error (3 kcal/mol) and an RMSD of 0.9 kcal/mol for the other five. The large error arose from the overstabilization of a protein/peptide salt bridge by the additive force field. Four of the ionic mutations were also simulated with the polarizable Drude force field, which represents the first test of this force field for protein/ligand binding free energy changes. The large error was eliminated and the RMS error for the four mutations was reduced from 1.8 to 1.2 kcal/mol. The overall accuracy of FEP indicates it can be used to understand PDZ/peptide binding. Importantly, our results show that for ionic mutations in buried regions, electronic polarization plays a significant role.
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10
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van Outersterp RE, Martens J, Berden G, Steill JD, Oomens J, Rijs AM. Structural characterization of nucleotide 5'-triphosphates by infrared ion spectroscopy and theoretical studies. Phys Chem Chem Phys 2018; 20:28319-28330. [PMID: 30398499 DOI: 10.1039/c8cp03314e] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The molecular family of nucleotide triphosphates (NTPs), with adenosine 5'-triphosphate (ATP) as its best-known member, is of high biochemical importance as their phosphodiester bonds form Nature's main means to store and transport energy. Here, gas-phase IR spectroscopic studies and supporting theoretical studies have been performed on adenosine 5'-triphosphate, cytosine 5'-triphosphate and guanosine 5'-triphosphate to elucidate the intrinsic structural properties of NTPs, focusing on the influence of the nucleobase and the extent of deprotonation. Mass spectrometric studies involving collision induced dissociation showed similar fragmentation channels for the three studied NTPs within a selected charge state. The doubly charged anions exhibit fragmentation similar to the energy-releasing hydrolysis reaction in nature, while the singly charged anions show different dominant fragmentation channels, suggesting that the charge state plays a significant role in the favorability of the hydrolysis reaction. A combination of infrared ion spectroscopy and quantum-chemical computations indicates that the singly charged anions of all NTPs are preferentially deprotonated at their β-phosphates, while the doubly-charged anions are dominantly αβ-deprotonated. The assigned three-dimensional structure differs for ATP and CTP on the one hand and GTP on the other, in the sense that ATP and CTP show no interaction between nucleobase and phosphate tail, while in GTP they are hydrogen bonded. This can be rationalized by considering the structure and geometry of the NTPs where the final three dimensional structure depends on a subtle balance between hydrogen bond strength, flexibility and steric hindrance.
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Affiliation(s)
- Rianne E van Outersterp
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7, 6525ED, Nijmegen, The Netherlands.
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11
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Kumar A, Satpati P. Principle of K+/Na+ selectivity in the active site of group II intron at various stages of self-splicing pathway. J Mol Graph Model 2018; 84:1-9. [DOI: 10.1016/j.jmgm.2018.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 04/16/2018] [Accepted: 05/10/2018] [Indexed: 10/16/2022]
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12
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Villa F, MacKerell AD, Roux B, Simonson T. Classical Drude Polarizable Force Field Model for Methyl Phosphate and Its Interactions with Mg 2. J Phys Chem A 2018; 122:6147-6155. [PMID: 29966419 PMCID: PMC6062457 DOI: 10.1021/acs.jpca.8b04418] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Phosphate groups are essential components of nucleic acids and proteins, whose interactions with solvent, metal ions, and ionic side chains help control folding and binding. Methyl phosphate (MP) represents a simple analog of phosphate moieties that are post-translation modifications in proteins and present at the termini of nucleic acids, among other environments. In the present study, we optimized parameters for use in polarizable molecular dynamics simulations of MP in its mono- and dianionic forms, MP- ≡ CH3HPO4- and MP2- ≡ CH3PO42-, along with P i2- ≡ HPO42-, in the context of the classical Drude oscillator model. Parameter optimization was done in a manner consistent with the remainder of the Drude molecular mechanics force field, choosing atomic charges and polarizabilities to reproduce molecular properties from quantum mechanics as well as experimental hydration free energies. Optimized parameters were similar to existing dimethyl phosphate parameters, with a few significant differences. The developed parameters were then used to compute magnesium binding affinities in aqueous solution, using alchemical molecular dynamics free energy simulations. Good agreement with experiment was obtained, and outer sphere binding was shown to be predominant for MP- and MP2-.
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Affiliation(s)
- Francesco Villa
- Laboratoire de Biochimie, CNRS UMR7654, Ecole Polytechnique , Palaiseau 91128 , France
| | - Alexander D MacKerell
- Department of Pharmaceutical Sciences, School of Pharmacy , University of Maryland , Baltimore , Maryland 21201 , United States
| | - Benoît Roux
- Department of Biochemistry and Molecular Biology , University of Chicago , Chicago , Illinois 60637 , United States
- Biosciences Division , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Thomas Simonson
- Laboratoire de Biochimie, CNRS UMR7654, Ecole Polytechnique , Palaiseau 91128 , France
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13
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Kumar A, Satpati P. Energetics of Preferential Binding of Retinoic Acid-Inducible Gene-I to Double-Stranded Viral RNAs with 5' Tri-/Diphosphate over 5' Monophosphate. ACS OMEGA 2018; 3:3786-3795. [PMID: 30023880 PMCID: PMC6044841 DOI: 10.1021/acsomega.7b02019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/23/2018] [Indexed: 06/08/2023]
Abstract
Retinoic acid-inducible gene-I (RIG-I) is a cytosolic sensor protein that recognizes viral RNAs and triggers an innate immune response in cells. Panhandle-like base-paired blunt-ended 5' ppp/pp-dsRNA is a characteristic feature of viral RNAs. Structural studies of RIG-I C-terminal domain bound 5' ppp/pp-dsRNA complexes show the direct interaction between all the 5' terminal phosphates (α, β, and γ) and protein, suggesting γ phosphate might be a major recognition determinant for RIG-I binding. Biochemical studies, however, suggest that 5' pp-dsRNA is the minimal determinant for RIG-I binding and antiviral response. Despite biochemical and structural studies, the origin of viral RNA recognition by RIG-I is an unsolved problem. X-ray structures of RIG-I bound dsRNA not only provide atomic insight into the interaction network but also provide sufficiently good models for computational studies. We report structure-based molecular dynamics (MD) free energy calculations to quantitatively estimate the energetics of RIG-I binding to dsRNA containing 5' ppp, 5' pp, and 5' p. The results suggest that RIG-I weakly discriminates between 5' ppp-dsRNA and 5' pp-dsRNA (favoring former) and strongly disfavors 5' p-dsRNA with respect to the rest. Interestingly, direct interaction between γ phosphate of 5' ppp-dsRNA and RIG-I is a robust feature of the MD simulations. dsRNA binding to RIG-I is associated with Mg2+ dissociation from the 5' phosphate/s of dsRNA. The higher Mg2+ dissociation penalty from 5' ppp-dsRNA with respect to 5' pp-dsRNA offsets most of the favorable interaction between RIG-I and γ phosphate of 5' ppp-dsRNA. This leads to weak discrimination between 5' ppp-dsRNA and 5' pp-dsRNA. 5' p-dsRNA is discriminated strongly because of the loss of interaction with RIG-I.
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14
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Wu X, Clavaguera C, Lagardère L, Piquemal JP, de la Lande A. AMOEBA Polarizable Force Field Parameters of the Heme Cofactor in Its Ferrous and Ferric Forms. J Chem Theory Comput 2018; 14:2705-2720. [PMID: 29630819 DOI: 10.1021/acs.jctc.7b01128] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We report the first parameters of the heme redox cofactors for the polarizable AMOEBA force field in both the ferric and ferrous forms. We consider two types of complexes, one with two histidine side chains as axial ligands and one with a histidine and a methionine side chain as ligands. We have derived permanent multipoles from second-order Møller-Plesset perturbation theory (MP2). The sets of parameters have been validated in a first step by comparison of AMOEBA interaction energies of heme and a collection of biologically relevant molecules with MP2 and Density Functional Theory (DFT) calculations. In a second validation step, we consider interaction energies with large aggregates comprising around 80 H2O molecules. These calculations are repeated for 30 structures extracted from semiempirical PM7 DM simulations. Very encouraging agreement is found between DFT and the AMOEBA force field, which results from an accurate treatment of electrostatic interactions. We finally report long (10 ns) MD simulations of cytochromes in two redox states with AMOEBA testing both the 2003 and 2014 AMOEBA water models. These simulations have been carried out with the TINKER-HP (High Performance) program. In conclusion, owing to their ubiquity in biology, we think the present work opens a wide array of applications of the polarizable AMOEBA force field on hemeproteins.
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Affiliation(s)
- Xiaojing Wu
- Laboratoire de Chimie Physique , Université Paris Sud - CNRS, Université Paris Saclay , 15 Avenue Jean Perrin , 91405 Orsay Cedex , France
| | - Carine Clavaguera
- Laboratoire de Chimie Physique , Université Paris Sud - CNRS, Université Paris Saclay , 15 Avenue Jean Perrin , 91405 Orsay Cedex , France
| | - Louis Lagardère
- Sorbonne Université, CNRS , Institut Parisien de Chimie Physique et Théorique (IP2CT) , 4 Place Jussieu , F-75005 , Paris , France.,Sorbonne Université , Institut des Sciences du Calcul et des Données (ISCD) , 4 place Jussieu , F-75005 , Paris , France
| | - Jean-Philip Piquemal
- Sorbonne Université, CNRS , Laboratoire de Chimie Théorique (LCT) , 4 Place Jussieu , F-75005 , Paris , France.,Department of Biomedical Engineering , The University of Texas at Austin , Austin , Texas 78712 , United States.,Institut Universitaire de France , 75005 , Paris , France
| | - Aurélien de la Lande
- Laboratoire de Chimie Physique , Université Paris Sud - CNRS, Université Paris Saclay , 15 Avenue Jean Perrin , 91405 Orsay Cedex , France
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15
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Peng X, Zhang Y, Chu H, Li Y, Zhang D, Cao L, Li G. Accurate Evaluation of Ion Conductivity of the Gramicidin A Channel Using a Polarizable Force Field without Any Corrections. J Chem Theory Comput 2016; 12:2973-82. [DOI: 10.1021/acs.jctc.6b00128] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Xiangda Peng
- Laboratory
of Molecular Modeling and
Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian
Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China
- Chinese
Academy of Science, University of Chinese Academy Sciences, Beijing 100049, P. R. China
| | - Yuebin Zhang
- Laboratory
of Molecular Modeling and
Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian
Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China
| | - Huiying Chu
- Laboratory
of Molecular Modeling and
Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian
Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China
| | - Yan Li
- Laboratory
of Molecular Modeling and
Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian
Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China
| | - Dinglin Zhang
- Laboratory
of Molecular Modeling and
Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian
Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China
| | - Liaoran Cao
- Laboratory
of Molecular Modeling and
Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian
Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China
| | - Guohui Li
- Laboratory
of Molecular Modeling and
Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian
Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China
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16
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Wang C, Huang W, Liao JL. QM/MM investigation of ATP hydrolysis in aqueous solution. J Phys Chem B 2015; 119:3720-6. [PMID: 25658024 DOI: 10.1021/jp512960e] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Adenosine-5'-triphosphate (ATP) hydrolysis represents a most important reaction in biology. Despite extensive research efforts, the mechanism for ATP hydrolysis in aqueous solution still remains under debate. Previous theoretical studies often predefined reaction coordinates to characterize the mechanism for ATP hydrolysis in water with Mg(2+) by evaluating free energy profiles through these preassumed reaction paths. In the present work, a nudged elastic band method is applied to identify the minimum energy path calculated with a hybrid quantum mechanics and molecular mechanics approach. Along the reaction path, the free energy profile was obtained to have a single transition state and the activation energy of 32.5 kcal/mol. This transition state bears a four-centered structure that describes a concerted nature of the reaction. In the More-O'Ferrall-Jencks diagram, the results show that the reaction proceeds through a concerted path before the system reaches the transition state and along an associative path after the transition state. In addition, the calculated reaction free energy is -7.0 kcal/mol, in good agreement with experiment, capturing the exothermic feature of MgATP(2-) hydrolysis in aqueous solution, whereas the reaction was often shown to be endothermic in the previous theoretical studies. As Mg(2+) is required for ATP hydrolysis in cells, its role in the reaction is also elucidated.
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Affiliation(s)
- Cui Wang
- Department of Chemical Physics, University of Science and Technology of China , 96 Jinzhai Road, 230026 Hefei, Anhui Province, People's Republic of China
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17
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Kumar M, Simonson T, Ohanessian G, Clavaguéra C. Structure and Thermodynamics of Mg:Phosphate Interactions in Water: A Simulation Study. Chemphyschem 2014; 16:658-65. [DOI: 10.1002/cphc.201402685] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Indexed: 01/04/2023]
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18
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Wang CY, Miller TF. Allosteric response and substrate sensitivity in peptide binding of the signal recognition particle. J Biol Chem 2014; 289:30868-30879. [PMID: 25237192 DOI: 10.1074/jbc.m114.584912] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
We characterize the conformational dynamics and substrate selectivity of the signal recognition particle (SRP) using a thermodynamic free energy cycle approach and microsecond timescale molecular dynamics simulations. The SRP is a central component of the co-translational protein targeting machinery that binds to the N-terminal signal peptide (SP) of nascent proteins. We determined the shift in relative conformational stability of the SRP upon substrate binding to quantify allosteric coupling between SRP domains. In particular, for dipeptidyl aminopeptidase, an SP that is recognized by the SRP for co-translational targeting, it is found that substrate binding induces substantial changes in the SRP toward configurations associated with targeting of the nascent protein, and it is found that the changes are modestly enhanced by a mutation that increases the hydrophobicity of the SP. However, for alkaline phosphatase, an SP that is recognized for post-translational targeting, substrate binding induces the reverse change in the SRP conformational distribution away from targeting configurations. Microsecond timescale trajectories reveal the intrinsic flexibility of the SRP conformational landscape and provide insight into recent single molecule studies by illustrating that 10-nm lengthscale changes between FRET pairs occur via the rigid-body movement of SRP domains connected by the flexible linker region. In combination, these results provide direct evidence for the hypothesis that substrate-controlled conformational switching in the SRP provides a mechanism for discriminating between different SPs and for connecting substrate binding to downstream steps in the protein targeting pathway.
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Affiliation(s)
- Connie Y Wang
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91106
| | - Thomas F Miller
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91106.
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19
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Simonson T, Aleksandrov A, Satpati P. Electrostatic free energies in translational GTPases: Classic allostery and the rest. Biochim Biophys Acta Gen Subj 2014; 1850:1006-1016. [PMID: 25047891 DOI: 10.1016/j.bbagen.2014.07.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Revised: 07/03/2014] [Accepted: 07/05/2014] [Indexed: 12/31/2022]
Abstract
GTPases typically switch between an inactive, OFF conformation and an active, ON conformation when a GDP ligand is replaced by GTP. Their ON/OFF populations and activity thus depend on the stabilities of four protein complexes, two apo-protein forms, and GTP/GDP in solution. A complete characterization is usually not possible experimentally and poses major challenges for simulations. We review the most important methodological challenges and we review thermodynamic data for two GTPases involved in translation of the genetic code: archaeal Initiation Factors 2 and 5B (aIF2, aIF5B). One main challenge is the multiplicity of states and conformations, including those of GTP/GDP in solution. Another is force field accuracy, especially for interactions of GTP/GDP with co-bound divalent Mg(2+) ions. The calculation of electrostatic free energies also poses specific challenges, and requires careful protocols. For aIF2, experiments and earlier simulations showed that it is a "classic" GTPase, with distinct ON/OFF conformations that prefer to bind GTP and GDP, respectively. For aIF5B, we recently proposed a non-classic mechanism, where the ON/OFF states differ only in the protonation state of Glu81 in the nucleotide binding pocket. This model is characterized here using free energy simulations. The methodological analysis should help future studies, while the aIF2, aIF5B examples illustrate the diversity of ATPase/GTPase mechanisms. This article is part of a Special Issue entitled Recent developments of molecular dynamics.
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Affiliation(s)
- Thomas Simonson
- Laboratoire de Biochimie (CNRS unit 7654), Department of Biology, Ecole Polytechnique, 91128 Palaiseau, France.
| | - Alexey Aleksandrov
- Laboratoire de Biochimie (CNRS unit 7654), Department of Biology, Ecole Polytechnique, 91128 Palaiseau, France
| | - Priyadarshi Satpati
- Laboratoire de Biochimie (CNRS unit 7654), Department of Biology, Ecole Polytechnique, 91128 Palaiseau, France; Department of Cell and Molecular Biology, University of Uppsala, Sweden
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20
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Lee HC, Hsu WC, Liu AL, Hsu CJ, Sun YC. Using thermodynamic integration MD simulation to compute relative protein–ligand binding free energy of a GSK3β kinase inhibitor and its analogs. J Mol Graph Model 2014; 51:37-49. [DOI: 10.1016/j.jmgm.2014.04.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 04/20/2014] [Accepted: 04/22/2014] [Indexed: 01/15/2023]
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21
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Semrouni D, Isley WC, Clavaguéra C, Dognon JP, Cramer CJ, Gagliardi L. Ab Initio Extension of the AMOEBA Polarizable Force Field to Fe2+. J Chem Theory Comput 2013; 9:3062-71. [DOI: 10.1021/ct400237r] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- David Semrouni
- Department of Chemistry, Chemical
Theory Center, and Supercomputing Institute, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota
55455, United States
| | - William C. Isley
- Department of Chemistry, Chemical
Theory Center, and Supercomputing Institute, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota
55455, United States
| | - Carine Clavaguéra
- Laboratoire
des Mécanismes
Réactionnels, Département de Chimie, École Polytechnique, CNRS, 91128 Palaiseau Cedex, France
| | - Jean-Pierre Dognon
- CEA/Saclay, UMR 3299 CEA/CNRS SIS2M, Laboratoire de Chimie de Coordination
des Eléments f, F-91191 Gif-sur-Yvette, France
| | - Christopher J. Cramer
- Department of Chemistry, Chemical
Theory Center, and Supercomputing Institute, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota
55455, United States
| | - Laura Gagliardi
- Department of Chemistry, Chemical
Theory Center, and Supercomputing Institute, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota
55455, United States
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22
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Simonson T, Satpati P. Simulating GTP:Mg and GDP:Mg with a simple force field: a structural and thermodynamic analysis. J Comput Chem 2012; 34:836-46. [PMID: 23280996 DOI: 10.1002/jcc.23207] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 11/12/2012] [Accepted: 11/28/2012] [Indexed: 11/06/2022]
Abstract
Di- and tri-phosphate nucleotides are essential cofactors for many proteins, usually in an Mg(2+) -bound form. Proteins like GTPases often detect the difference between NDP and NTP and respond by changing conformations. To study such complexes, simple, fixed charge force fields have been used, which allow long simulations and precise free energy calculations. The preference for NTP or NDP binding depends on many factors, including ligand structure and Mg(2+) coordination and the changes they undergo upon binding. Here, we use a simple force field to examine two Mg(2+) coordination modes for the unbound GDP and GTP: direct, or "Inner Sphere" (IS) coordination by one or more phosphate oxygens and indirect, "Outer Sphere" (OS) coordination involving one or more bridging waters. We compare GTP: and GDP:Mg binding with OS and IS coordination; combining the results with experimental data then indicates that GTP prefers the latter. We also examine different kinds of IS coordination and their sensitivity to a key force field parameter: the optimal Mg:oxygen van der Waals distance Rmin . Increasing Rmin improves the Mg:oxygen distances, the GTP: and GDP:Mg binding affinities, and the fraction of GTP:Mg with β + γ phosphate coordination, but does not improve or change the GTP/GDP affinity difference, which remains much larger than experiment. It has no effect on the free energy of GDP binding to a GTPase.
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Affiliation(s)
- Thomas Simonson
- Department of Biology, Laboratoire de Biochimie (CNRS UMR7654), Ecole Polytechnique, 91128 Palaiseau, France.
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23
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Computation of relative binding free energy for an inhibitor and its analogs binding with Erk kinase using thermodynamic integration MD simulation. J Comput Aided Mol Des 2012; 26:1159-69. [DOI: 10.1007/s10822-012-9606-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 09/10/2012] [Indexed: 01/17/2023]
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24
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Simonson T, Satpati P. Nucleotide recognition by the initiation factor aIF5B: free energy simulations of a neoclassical GTPase. Proteins 2012; 80:2742-57. [PMID: 22887821 DOI: 10.1002/prot.24158] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 07/16/2012] [Accepted: 07/28/2012] [Indexed: 12/13/2022]
Abstract
The GTPase aIF5B is a universally conserved initiation factor that assists ribosome assembly. Crystal structures of its nucleotide complexes, X-ray(GTP) and X-ray(GDP), are similar in the nucleotide vicinity, but differ in the orientation of a distant domain IV. This has led to two, contradictory, mechanistic models. One postulates that X-ray(GTP) and X-ray(GDP) are, respectively, the active, "ON" and the inactive, "OFF" states; the other postulates that both structures are OFF, whereas the ON state is still uncharacterized. We study GTP/GDP binding using molecular dynamics and a continuum electrostatic free energy method. We predict that X-ray(GTP) has a ≈ 3 kcal/mol preference to bind GDP, apparently contradicting its assignment as ON. However, the preference arises mainly from a single, nearby residue from the switch 2 motif: Glu81, which becomes protonated upon GTP binding, with a free energy cost of about 4 kcal/mol. We then propose a different model, where Glu81 protonation/deprotonation defines the ON/OFF states. With this model, the X-ray(GTP):GTP complex, with its protonated Glu81, is ON, whereas X-ray(GTP):GDP is OFF. The model postulates that distant conformational changes such as domain IV rotation are "uncoupled" from GTP/GDP exchange and do not affect the relative GTP/GDP binding affinities. We analyze the model using a general thermodynamic framework for GTPases. It yields rather precise predictions for the nucleotide specificities of each state, and the state specificities of each nucleotide, which are roughly comparable to the homologues IF2 and aIF2, despite the lack of any conformational switching in the model.
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Affiliation(s)
- Thomas Simonson
- Department of Biology, Laboratoire de Biochimie (CNRS UMR7654), Ecole Polytechnique, 91128 Palaiseau, France.
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25
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Satpati P, Simonson T. Conformational selection through electrostatics: Free energy simulations of GTP and GDP binding to archaeal initiation factor 2. Proteins 2012; 80:1264-82. [PMID: 22275120 DOI: 10.1002/prot.24023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 11/29/2011] [Accepted: 12/13/2011] [Indexed: 11/05/2022]
Abstract
Archaeal Initiation Factor 2 is a GTPase involved in protein biosynthesis. In its GTP-bound, "ON" conformation, it binds an initiator tRNA and carries it to the ribosome. In its GDP-bound, "OFF" conformation, it dissociates from tRNA. To understand the specific binding of GTP and GDP and their dependence on the conformational state, molecular dynamics free energy simulations were performed. The ON state specificity was predicted to be weak, with a GTP/GDP binding free energy difference of -1 kcal/mol, favoring GTP. The OFF state specificity is larger, 4 kcal/mol, favoring GDP. The overall effects result from a competition among many interactions in several complexes. To interpret them, we use a simpler, dielectric continuum model. Several effects are robust with respect to the model details. Both nucleotides have a net negative charge, so that removing them from solvent into the binding pocket carries a desolvation penalty, which is large for the ON state, and strongly disfavors GTP binding compared to GDP. Short-range interactions between the additional GTP phosphate group and ionized sidechains in the binding pocket offset most, but not all of the desolvation penalty; more distant groups also contribute significantly, and the switch 1 loop only slightly. The desolvation penalty is lower for the more open, wetter OFF state, and the GTP/GDP difference much smaller. Short-range interactions in the binding pocket and with more distant groups again make a significant contribution. Overall, the simulations help explain how conformational selection is achieved with a single phosphate group.
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Affiliation(s)
- Priyadarshi Satpati
- Laboratoire de Biochimie (CNRS UMR7654), Department of Biology, Ecole Polytechnique, CNRS, 91128 Palaiseau Cedex, France
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26
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Satpati P, Simonson T. Conformational selection by the aIF2 GTPase: a molecular dynamics study of functional pathways. Biochemistry 2011; 51:353-61. [PMID: 22165972 DOI: 10.1021/bi201675n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Archaeal initiation factor 2 (aIF2) is a GTPase involved in protein biosynthesis. In its GTP-bound, "ON" conformation, it binds an initiator tRNA and carries it to the ribosome. In its GDP-bound, "OFF" conformation, it dissociates from tRNA. To improve our understanding of the role of each conformational state in the aIF2 "life cycle", we start from the state immediately after GTP hydrolysis, ON:GDP:P(i) (where P(i) is inorganic phosphate), and consider the possible next steps on the pathway to the OFF:GDP product. The first possibility is P(i) dissociation, leading to ON:GDP, which could then relax into OFF:GDP. We use molecular dynamics simulations to compute the P(i) dissociation free energy and show that dissociation is highly favorable. The second possibility is conformational relaxation into the OFF state before P(i) dissociation, to form OFF:GDP:P(i). We estimate the corresponding free energy approximately, 2 ± 3.5 kcal/mol, so that this is an uphill or weakly downhill process. A third possibility is relaxation into another conformation, neither ON nor OFF. Indeed, a third, "MIXED" conformation was seen recently in a crystal structure of the aIF2:GDP:P(i) complex. For this conformational state, P(i) dissociation is weakly unfavorable, in contrast to the ON and OFF states. From this, we will deduce that if the MIXED:GDP complex is not too unstable, the ON:GDP:P(i) → MIXED:GDP:P(i) transformation is a downhill process, which can occur spontaneously. This suggests that the MIXED state could be a functional intermediate.
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Affiliation(s)
- Priyadarshi Satpati
- Laboratoire de Biochimie (CNRS UMR7654), Department of Biology, Ecole Polytechnique, 91128 Palaiseau, France
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