1
|
Dias RVR, Ferreira CTA, Jennings PA, Whitford PC, Oliveira LCD. Csk αC Helix: A Computational Analysis of an Essential Region for Conformational Transitions. J Phys Chem B 2022; 126:10587-10596. [PMID: 36512419 DOI: 10.1021/acs.jpcb.2c05408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Conformational changes are an essential feature for the function of some dynamic proteins. Understanding the mechanism of such motions may allow us to identify important properties, which may be directly related to the regulatory function of a protein. Also, this knowledge may be employed for a rational design of drugs that can shift the balance between active and inactive conformations, as well as affect the kinetics of the activation process. Here, the conformational changes in carboxyl-terminal Src kinase, the major catalytic repressor to the Src family of kinases, was investigated, and it was proposed as a functionally related hypothesis. A Cα Structure-Based Model (Cα-SBM) was applied to provide a description of the overall conformational landscape and further analysis complemented by detailed molecular dynamics simulations. As a first approach to Cα-SBM simulations, reversible transitions between active (closed) and inactive (open) forms were modeled as fluctuations between these two energetic basins. It was found that, in addition to the interdomain Carboxyl-terminal SRC Kinase (Csk) correlated motions, a conformational change in the αC helix is required for a complete conformational transition. The result reveals this as an important region of transition control and domain coordination. Restrictions in the αC helix region of the Csk protein were performed, and the analyses showed a direct correlation with the global conformational changes, with this location being propitious for future studies of ligands. Also, the Src Homology 3 (SH3) and SH3 plus Src Homology 2 (SH2) domains were excluded for a direct comparison with experimental results previously published. Simulations where the SH3 was deleted presented a reduction of the transitions during the simulations, while the SH3-SH2 deletion vanishes the Csk transitions, corroborating the experimental results mentioned and linking the conformational changes with the catalytic functionality of Csk. The study was complemented by the introduction of a known kinase inhibitor close to the Csk αC helix region where its consequences for the kinetic behavior and domain displacement of Csk were verified through detailed molecular dynamics. The findings describe the mechanisms involving the Csk αC helix for the transitions and also support the dynamic correlation between SH3 and SH2 domains against the Csk lobes and how local energetic restrictions or interactions in the Csk αC helix can play an important role for long-range motions. The results also allow speculation if the Csk activity is restricted to one specific conformation or a consequence of a state transition, this point being a target for future studies. However, the αC helix is revealed as a potential region for rational drug design.
Collapse
Affiliation(s)
- Raphael Vinicius Rodrigues Dias
- São Paulo State University (Unesp), Department of Physics, Institute of Biosciences, Humanities and Exact Sciences, Rua Cristóvão Colombo, 2265, São José do Rio Preto, São Paulo15054-000, Brazil
| | - Carolina Tatiani Alves Ferreira
- São Paulo State University (Unesp), Department of Physics, Institute of Biosciences, Humanities and Exact Sciences, Rua Cristóvão Colombo, 2265, São José do Rio Preto, São Paulo15054-000, Brazil
| | - Patricia Ann Jennings
- University of California, San Diego, 9500 Gilman Drive, Natural Science Building #3110, La Jolla, California92093, United States
| | - Paul Charles Whitford
- Northeastern University, Department of Physics and Center for Theoretical Biological Physics, 360 Huntington Avenue, Boston, Massachusetts02115, United States
| | - Leandro Cristante de Oliveira
- São Paulo State University (Unesp), Department of Physics, Institute of Biosciences, Humanities and Exact Sciences, Rua Cristóvão Colombo, 2265, São José do Rio Preto, São Paulo15054-000, Brazil
| |
Collapse
|
2
|
Whitford PC. Overview of the Biomolecular Association and Dynamics session at the 20th IUPAB congress, 45th Brazilian congress of SBBF, and the 50th annual meeting of SBBq. Biophys Rev 2022; 13:863-865. [PMID: 35059009 DOI: 10.1007/s12551-021-00884-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 11/01/2021] [Indexed: 05/31/2023] Open
Abstract
In this session, experts in molecular biophysics described the dynamics of biopolymers across a wide range of length and time scales. This discussion highlighted numerous techniques that span from highly detailed simulations, to coarse-grained theoretical models, as well as high-resolution structural analysis. The topics were equally diverse, where there was discussion of biological processes at small (individual atoms), intermediate (assemblies) and very large scales (phase separation).
Collapse
Affiliation(s)
- Paul Charles Whitford
- Department of Physics and Center for Theoretical Biological Physics, Northeastern University, Boston, MA USA
| |
Collapse
|
3
|
Dodero-Rojas E, Onuchic JN, Whitford PC. Sterically confined rearrangements of SARS-CoV-2 Spike protein control cell invasion. eLife 2021; 10:70362. [PMID: 34463614 PMCID: PMC8456623 DOI: 10.7554/elife.70362] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 08/06/2021] [Indexed: 12/13/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is highly contagious, and transmission involves a series of processes that may be targeted by vaccines and therapeutics. During transmission, host cell invasion is controlled by a large-scale (200–300 Å) conformational change of the Spike protein. This conformational rearrangement leads to membrane fusion, which creates transmembrane pores through which the viral genome is passed to the host. During Spike-protein-mediated fusion, the fusion peptides must be released from the core of the protein and associate with the host membrane. While infection relies on this transition between the prefusion and postfusion conformations, there has yet to be a biophysical characterization reported for this rearrangement. That is, structures are available for the endpoints, though the intermediate conformational processes have not been described. Interestingly, the Spike protein possesses many post-translational modifications, in the form of branched glycans that flank the surface of the assembly. With the current lack of data on the pre-to-post transition, the precise role of glycans during cell invasion has also remained unclear. To provide an initial mechanistic description of the pre-to-post rearrangement, an all-atom model with simplified energetics was used to perform thousands of simulations in which the protein transitions between the prefusion and postfusion conformations. These simulations indicate that the steric composition of the glycans can induce a pause during the Spike protein conformational change. We additionally show that this glycan-induced delay provides a critical opportunity for the fusion peptides to capture the host cell. In contrast, in the absence of glycans, the viral particle would likely fail to enter the host. This analysis reveals how the glycosylation state can regulate infectivity, while providing a much-needed structural framework for studying the dynamics of this pervasive pathogen.
Collapse
Affiliation(s)
- Esteban Dodero-Rojas
- Center for Theoretical Biological Physics, Rice University, Houston, United States
| | - Jose N Onuchic
- Center for Theoretical Biological Physics, Rice University, Houston, United States.,Department of Physics and Astronomy, Rice University, Houston, United States.,Department of Chemistry, Rice University, Houston, United States.,Department of Biosciences, Rice University, Houston, United States
| | - Paul Charles Whitford
- Center for Theoretical Biological Physics, Northeastern University, Boston, United States.,Department of Physics, Northeastern University, Boston, United States
| |
Collapse
|
4
|
Abstract
Protein synthesis by the ribosome is coordinated by an intricate series of large-scale conformational rearrangements. Structural studies can provide information about long-lived states, however biological kinetics are controlled by the intervening free-energy barriers. While there has been progress describing the energy landscapes of bacterial ribosomes, very little is known about the energetics of large-scale rearrangements in eukaryotic systems. To address this topic, we constructed an all-atom model with simplified energetics and performed simulations of subunit rotation in the yeast ribosome. In these simulations, the small subunit (SSU; ~1MDa) undergoes spontaneous and reversible rotations (~8°). By enabling the simulation of this rearrangement under equilibrium conditions, these calculations provide initial insights into the molecular factors that control dynamics in eukaryotic ribosomes. Through this, we are able to identify specific inter-subunit interactions that have a pronounced influence on the rate-limiting free-energy barrier. We also show that, as a result of changes in molecular flexibility, the thermodynamic balance between the rotated and unrotated states is temperature-dependent. This effect may be interpreted in terms of differential molecular flexibility within the rotated and unrotated states. Together, these calculations provide a foundation, upon which the field may begin to dissect the energetics of these complex molecular machines.
Collapse
Affiliation(s)
- Frederico Campos Freitas
- Laboratório de Biofísica Teórica, Departamento de Física, Instituto de Ciências Exatas, Naturais e Educação, Universidade Federal do Triângulo Mineiro, Uberaba, MG, Brazil
| | - Gabriele Fuchs
- Department of Biological Sciences, The RNA Institute, University at Albany 1400 Washington Ave, Albany, NY,12222
| | - Ronaldo Junio de Oliveira
- Laboratório de Biofísica Teórica, Departamento de Física, Instituto de Ciências Exatas, Naturais e Educação, Universidade Federal do Triângulo Mineiro, Uberaba, MG, Brazil
| | - Paul Charles Whitford
- Department of Physics, Northeastern University, 360 Huntington Ave, Boston, MA 02115
- Center for Theoretical Biological Physics, Northeastern University, 360 Huntington Ave, Boston, MA 02115
| |
Collapse
|
5
|
Yang H, Noel J, Charles Whitford P. Anisotropic Fluctuations in the Ribosome Determine aa-tRNA Kinetics. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.2186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
|
6
|
Levi M, Nguyen K, Dukaye L, Whitford PC. Quantifying the Relationship between Single-Molecule Probes and Subunit Rotation in the Ribosome. Biophys J 2018; 113:2777-2786. [PMID: 29262370 DOI: 10.1016/j.bpj.2017.10.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 10/12/2017] [Accepted: 10/16/2017] [Indexed: 11/18/2022] Open
Abstract
A major challenge in the study of biomolecular assemblies is to identify reaction coordinates that precisely monitor conformational rearrangements. This is central to the interpretation of single-molecule fluorescence resonance energy transfer measurements, where the observed dynamics depends on the labeling strategy. As an example, different probes of subunit rotation in the ribosome have provided qualitatively distinct descriptions. In one study, changes in fluorescence suggested that the 30S body undergoes a single rotation/back-rotation cycle during the process of mRNA-tRNA translocation. In contrast, an alternate assay implicated the presence of reversible rotation events before completing translocation. For future single-molecule experiments to unambiguously measure the relationship between subunit rotation and translocation, it is necessary to rationalize these conflicting descriptions. To this end, we have simulated hundreds of spontaneous subunit rotation events (≈8°) using a residue-level coarse-grained model of the ribosome. We analyzed nine different reaction coordinates and found that the apparently inconsistent measurements are likely a consequence of ribosomal flexibility. Further, we propose a metric for quantifying the degree of energetic coupling between experimentally measured degrees of freedom and subunit rotation. This analysis provides a physically grounded framework that can guide the development of more precise single-molecule techniques.
Collapse
Affiliation(s)
- Mariana Levi
- Department of Physics, Northeastern University, Boston, Massachusetts
| | - Kien Nguyen
- Department of Physics, Northeastern University, Boston, Massachusetts
| | - Liah Dukaye
- Department of Physics, Northeastern University, Boston, Massachusetts
| | | |
Collapse
|
7
|
|
8
|
Yang H, Whitford PC. The Role of L11 Stalk Fluctuations in aa-tRNA Accommodation. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
|
9
|
Noel JK, Chahine J, Leite VBP, Whitford PC. Capturing transition paths and transition states for conformational rearrangements in the ribosome. Biophys J 2016; 107:2881-2890. [PMID: 25517153 DOI: 10.1016/j.bpj.2014.10.022] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 09/25/2014] [Accepted: 10/16/2014] [Indexed: 11/26/2022] Open
Abstract
To reveal the molecular determinants of biological function, one seeks to characterize the interactions that are formed in conformational and chemical transition states. In other words, what interactions govern the molecule's energy landscape? To accomplish this, it is necessary to determine which degrees of freedom can unambiguously identify each transition state. Here, we perform simulations of large-scale aminoacyl-transfer RNA (aa-tRNA) rearrangements during accommodation on the ribosome and project the dynamics along experimentally accessible atomic distances. From this analysis, we obtain evidence for which coordinates capture the correct number of barrier-crossing events and accurately indicate when the aa-tRNA is on a transition path. Although a commonly used coordinate in single-molecule experiments performs poorly, this study implicates alternative coordinates along which rearrangements are accurately described as diffusive movements across a one-dimensional free-energy profile. From this, we provide the theoretical foundation required for single-molecule techniques to uncover the energy landscape governing aa-tRNA selection by the ribosome.
Collapse
Affiliation(s)
- Jeffrey K Noel
- Center for Theoretical Biological Physics, Rice University, Houston, Texas
| | - Jorge Chahine
- Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista, São José do Rio Preto, Brazil
| | - Vitor B P Leite
- Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista, São José do Rio Preto, Brazil
| | | |
Collapse
|
10
|
Abstract
The ever-increasing capacity of computing resources has extended ribosome calculations from the study of small-scale fluctuations to large-scale barrier-crossing processes. As the field of computational/theoretical biophysics shifts focus to large-scale conformational transitions, there is a growing need for a systematic framework to interpret and analyze ribosome dynamics. To this end, energy landscape principles, largely developed for the study of biomolecular folding, have proven to be invaluable. These tools not only provide a foundation for describing simulations but can be used to reconcile experimental results, as well. In this review, I will discuss recent efforts to employ computational methods to reveal the characteristics of the ribosome's landscape and how these studies can help guide a new generation of experiments that more closely probe the underlying energetics. As a result of these investigations, general principles about ribosome function are beginning to emerge, including that: (1) small-scale fluctuations are the result of structure, rather than detailed energetics, (2) molecular flexibility leads to entropically favored rearrangements, and (3) tRNA dynamics may be accurately described as diffusive movement across an energy landscape.
Collapse
Affiliation(s)
- Paul Charles Whitford
- Department of Physics, Northeastern University Dana Research Center 123, 360 Huntington Ave, Boston, MA, 02115, USA.
| |
Collapse
|
11
|
Nguyen K, Charles Whitford P. 68 Simulating mRNA-tRNA translocation through the ribosome. J Biomol Struct Dyn 2015. [DOI: 10.1080/07391102.2015.1032685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
12
|
Nguyen K, Whitford PC. Simulating Ribosome Dynamics and tRNA Translocation. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.2140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
|
13
|
|
14
|
Whitford PC, Onuchic JN, Wolynes PG. Energy landscape along an enzymatic reaction trajectory: hinges or cracks? HFSP J 2008; 2:61-4. [PMID: 19404472 DOI: 10.2976/1.2894846] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Indexed: 11/19/2022]
Abstract
Are the most dynamically flexible regions around the equilibrium structure of an enzyme the same regions involved in the transition state for rate limiting processes involved in the enzymatic reaction? Kern and-coworkers (Wolf-Watzet al., 2004; Henzler-Wildman et al., 2007a, 2007b) have shown that insights about functionally relevant motions that determine the overall enzyme turnover rate can be obtained by investigating conformational dynamics around the equilibrium basin of the enzyme adenylate kinase. An allosteric change in protein structure turns out to be the controlling process. In this commentary we compare results of this study with earlier predictions of the route by which the enzyme undergoes its conformational change. These predictions are based on the idea that the energy surface for the protein is determined by the end structures of the conformational change. A key issue is whether the protein moves by specific hinges or whether it "cracks" and accesses partially unfolded states during its structural change.
Collapse
|