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Krepl M, Pokorná P, Mlýnský V, Stadlbauer P, Šponer J. Spontaneous binding of single-stranded RNAs to RRM proteins visualized by unbiased atomistic simulations with a rescaled RNA force field. Nucleic Acids Res 2022; 50:12480-12496. [PMID: 36454011 PMCID: PMC9757038 DOI: 10.1093/nar/gkac1106] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 10/25/2022] [Accepted: 11/04/2022] [Indexed: 12/03/2022] Open
Abstract
Recognition of single-stranded RNA (ssRNA) by RNA recognition motif (RRM) domains is an important class of protein-RNA interactions. Many such complexes were characterized using nuclear magnetic resonance (NMR) and/or X-ray crystallography techniques, revealing ensemble-averaged pictures of the bound states. However, it is becoming widely accepted that better understanding of protein-RNA interactions would be obtained from ensemble descriptions. Indeed, earlier molecular dynamics simulations of bound states indicated visible dynamics at the RNA-RRM interfaces. Here, we report the first atomistic simulation study of spontaneous binding of short RNA sequences to RRM domains of HuR and SRSF1 proteins. Using a millisecond-scale aggregate ensemble of unbiased simulations, we were able to observe a few dozen binding events. HuR RRM3 utilizes a pre-binding state to navigate the RNA sequence to its partially disordered bound state and then to dynamically scan its different binding registers. SRSF1 RRM2 binding is more straightforward but still multiple-pathway. The present study necessitated development of a goal-specific force field modification, scaling down the intramolecular van der Waals interactions of the RNA which also improves description of the RNA-RRM bound state. Our study opens up a new avenue for large-scale atomistic investigations of binding landscapes of protein-RNA complexes, and future perspectives of such research are discussed.
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Affiliation(s)
| | - Pavlína Pokorná
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic,National Center for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Vojtěch Mlýnský
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
| | - Petr Stadlbauer
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
| | - Jiří Šponer
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
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Piatt SC, Loparo JJ, Price AC. The Role of Noncognate Sites in the 1D Search Mechanism of EcoRI. Biophys J 2019; 116:2367-2377. [PMID: 31113551 PMCID: PMC6588823 DOI: 10.1016/j.bpj.2019.04.035] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 04/18/2019] [Accepted: 04/29/2019] [Indexed: 02/02/2023] Open
Abstract
A one-dimensional (1D) search is an essential step in DNA target recognition. Theoretical studies have suggested that the sequence dependence of 1D diffusion can help resolve the competing demands of a fast search and high target affinity, a conflict known as the speed-selectivity paradox. The resolution requires that the diffusion energy landscape is correlated with the underlying specific binding energies. In this work, we report observations of a 1D search by quantum dot-labeled EcoRI. Our data supports the view that proteins search DNA via rotation-coupled sliding over a corrugated energy landscape. We observed that whereas EcoRI primarily slides along DNA at low salt concentrations, at higher concentrations, its diffusion is a combination of sliding and hopping. We also observed long-lived pauses at genomic star sites, which differ by a single nucleotide from the target sequence. To reconcile these observations with prior biochemical and structural data, we propose a model of search in which the protein slides over a sequence-independent energy landscape during fast search but rapidly interconverts with a "hemispecific" binding mode in which a half site is probed. This half site interaction stabilizes the transition to a fully specific mode of binding, which can then lead to target recognition.
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Affiliation(s)
- Sadie C Piatt
- Department of Chemistry and Physics, Emmanuel College, Boston, Massachusetts
| | - Joseph J Loparo
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts.
| | - Allen C Price
- Department of Chemistry and Physics, Emmanuel College, Boston, Massachusetts.
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Rad4 recognition-at-a-distance: Physical basis of conformation-specific anomalous diffusion of DNA repair proteins. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 127:93-104. [PMID: 27939760 DOI: 10.1016/j.pbiomolbio.2016.12.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 12/06/2016] [Indexed: 11/20/2022]
Abstract
Since Robert Brown's first observations of random walks by pollen particles suspended in solution, the concept of diffusion has been subject to countless theoretical and experimental studies in diverse fields from finance and social sciences, to physics and biology. Diffusive transport of macromolecules in cells is intimately linked to essential cellular functions including nutrient uptake, signal transduction, gene expression, as well as DNA replication and repair. Advancement in experimental techniques has allowed precise measurements of these diffusion processes. Mathematical and physical descriptions and computer simulations have been applied to model complicated biological systems in which anomalous diffusion, in addition to simple Brownian motion, was observed. The purpose of this review is to provide an overview of the major physical models of anomalous diffusion and corresponding experimental evidence on the target search problem faced by DNA-binding proteins, with an emphasis on DNA repair proteins and the role of anomalous diffusion in DNA target recognition.
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Hong F, Brizendine RK, Carter MS, Alcala DB, Brown AE, Chattin AM, Haldeman BD, Walsh MP, Facemyer KC, Baker JE, Cremo CR. Diffusion of myosin light chain kinase on actin: A mechanism to enhance myosin phosphorylation rates in smooth muscle. ACTA ACUST UNITED AC 2016; 146:267-80. [PMID: 26415568 PMCID: PMC4586593 DOI: 10.1085/jgp.201511483] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Smooth muscle myosin (SMM) light chain kinase (MLCK) phosphorylates SMM, thereby activating the ATPase activity required for muscle contraction. The abundance of active MLCK, which is tightly associated with the contractile apparatus, is low relative to that of SMM. SMM phosphorylation is rapid despite the low ratio of MLCK to SMM, raising the question of how one MLCK rapidly phosphorylates many SMM molecules. We used total internal reflection fluorescence microscopy to monitor single molecules of streptavidin-coated quantum dot-labeled MLCK interacting with purified actin, actin bundles, and stress fibers of smooth muscle cells. Surprisingly, MLCK and the N-terminal 75 residues of MLCK (N75) moved on actin bundles and stress fibers of smooth muscle cell cytoskeletons by a random one-dimensional (1-D) diffusion mechanism. Although diffusion of proteins along microtubules and oligonucleotides has been observed previously, this is the first characterization to our knowledge of a protein diffusing in a sustained manner along actin. By measuring the frequency of motion, we found that MLCK motion is permitted only if acto-myosin and MLCK-myosin interactions are weak. From these data, diffusion coefficients, and other kinetic and geometric considerations relating to the contractile apparatus, we suggest that 1-D diffusion of MLCK along actin (a) ensures that diffusion is not rate limiting for phosphorylation, (b) allows MLCK to locate to areas in which myosin is not yet phosphorylated, and (c) allows MLCK to avoid getting "stuck" on myosins that have already been phosphorylated. Diffusion of MLCK along actin filaments may be an important mechanism for enhancing the rate of SMM phosphorylation in smooth muscle.
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Affiliation(s)
- Feng Hong
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, NV 99557
| | - Richard K Brizendine
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, NV 99557
| | - Michael S Carter
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, NV 99557
| | - Diego B Alcala
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, NV 99557
| | - Avery E Brown
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, NV 99557
| | - Amy M Chattin
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, NV 99557
| | - Brian D Haldeman
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, NV 99557
| | - Michael P Walsh
- Department of Biochemistry and Molecular Biology, University of Calgary Faculty of Medicine, Calgary, Alberta T2N 4N1, Canada
| | - Kevin C Facemyer
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, NV 99557
| | - Josh E Baker
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, NV 99557
| | - Christine R Cremo
- Department of Biochemistry and Molecular Biology, University of Nevada School of Medicine, Reno, NV 99557
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Klein M, Chandradoss SD, Depken M, Joo C. Why Argonaute is needed to make microRNA target search fast and reliable. Semin Cell Dev Biol 2016; 65:20-28. [PMID: 27235676 DOI: 10.1016/j.semcdb.2016.05.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 05/19/2016] [Accepted: 05/21/2016] [Indexed: 10/21/2022]
Abstract
MicroRNA (miRNA) interferes with the translation of cognate messenger RNA (mRNA) by finding, preferentially binding, and marking it for degradation. To facilitate the search process, Argonaute (Ago) proteins come together with miRNA, forming a dynamic search complex. In this review we use the language of free-energy landscapes to discuss recent single-molecule and high-resolution structural data in the light of theoretical work appropriated from the study of transcription-factor search. We suggest that experimentally observed internal states of the Ago-miRNA search complex may have the explicit biological function of speeding up search while maintaining specificity.
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Affiliation(s)
- Misha Klein
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, Delft, 2629HZ, The Netherlands
| | - Stanley D Chandradoss
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, Delft, 2629HZ, The Netherlands
| | - Martin Depken
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, Delft, 2629HZ, The Netherlands.
| | - Chirlmin Joo
- Kavli Institute of NanoScience and Department of BioNanoScience, Delft University of Technology, Delft, 2629HZ, The Netherlands.
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