Molecular mechanisms underlying deoxy‐ADP.Pi activation of pre‐powerstroke myosin

Nowakowski, Sarah G.; Regnier, Michael; Daggett, Valerie

doi:10.1002/pro.3121

Cited by 14 publications

(23 citation statements)

References 62 publications

(113 reference statements)

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“…Leads to Increased Binding Kinetics. In prepowerstroke myosin, dADP.Pi allosterically affects myosin, resulting in a structural rearrangement of the nucleotide binding pocket that translates to an altered actin-binding region of myosin (8). However, the effects of the altered actin-binding region of myosin by dADP.Pi on the actin-myosin association kinetics and energetics remained unknown.…”

Section: Electrostatic Restructuring Of the Actin-myosin Interface VImentioning

confidence: 99%

“…Chemomechanical studies suggest that the dATP-mediated force augmentation occurs by increasing cross-bridge binding and cycling rates (4-7), but a precise structural explanation for this is lacking. A recent computational study using molecular dynamics simulations suggests that dATP behaves as an allosteric effector of prepowerstroke myosin, such that when 2-deoxy-adenosine 5′-diphosphate and inorganic phosphate (dADP.Pi) are in the nucleotide binding pocket, local structural changes lead to exposure of more positively charged residues on the actin-binding surface of myosin compared withADP.Pi (8). This led us to hypothesize that dATP increases the electrostatic…”

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confidence: 99%

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Cardiac myosin activation with 2-deoxy-ATP via increased electrostatic interactions with actin

Powers

Yuan

McCabe

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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The naturally occurring nucleotide 2-deoxy-adenosine 5′-triphosphate (dATP) can be used by cardiac muscle as an alternative energy substrate for myosin chemomechanical activity. We and others have previously shown that dATP increases contractile force in normal hearts and models of depressed systolic function, but the structural basis of these effects has remained unresolved. In this work, we combine multiple techniques to provide structural and functional information at the angstrom-nanometer and millisecond time scales, demonstrating the ability to make both structural measurements and quantitative kinetic estimates of weak actin–myosin interactions that underpin sarcomere dynamics. Exploiting dATP as a molecular probe, we assess how small changes in myosin structure translate to electrostatic-based changes in sarcomere function to augment contractility in cardiac muscle. Through Brownian dynamics simulation and computational structural analysis, we found that deoxy-hydrolysis products [2-deoxy-adenosine 5′-diphosphate (dADP) and inorganic phosphate (Pi)] bound to prepowerstroke myosin induce an allosteric restructuring of the actin-binding surface on myosin to increase the rate of cross-bridge formation. We then show experimentally that this predicted effect translates into increased electrostatic interactions between actin and cardiac myosin in vitro. Finally, using small-angle X-ray diffraction analysis of sarcomere structure, we demonstrate that the proposed increased electrostatic affinity of myosin for actin causes a disruption of the resting conformation of myosin motors, resulting in their repositioning toward the thin filament before activation. The dATP-mediated structural alterations in myosin reported here may provide insight into an improved criterion for the design or selection of small molecules to be developed as therapeutic agents to treat systolic dysfunction.

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Section: Electrostatic Restructuring Of the Actin-myosin Interface VImentioning

confidence: 99%

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confidence: 99%

Cardiac myosin activation with 2-deoxy-ATP via increased electrostatic interactions with actin

Powers

Yuan

McCabe

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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“…Previous computational works have focused so far on the effect of nucleotide [32] or actin binding [33] on myosin dynamics, the interactions between actin and myosin [34], the release of Pi [35], the modelling of the recovery stroke [36][37][38][39] or in general of the coupling between the actin binding site, the nucleotide binding site and the converter [40][41][42][43]. A significant part of these studies used enhanced sampling techniques to accelerate the transitions between the different states in the actomyosin cycle [35, 36, 38-41, 43, 44], while unbiased simulations with length > = 50 ns have been performed only recently [32,33,37,45] thanks to the increase of the available computational power.…”

Section: Discussionmentioning

confidence: 99%

Allosteric Modulation of Cardiac Myosin Dynamics by Omecamtiv Mecarbil

Hashem

Tiberti

Fornili

2018

Biophysical Journal

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New promising avenues for the pharmacological treatment of skeletal and heart muscle diseases rely on direct sarcomeric modulators, which are molecules that can directly bind to sarcomeric proteins and either inhibit or enhance their activity. A recent breakthrough has been the discovery of the myosin activator omecamtiv mecarbil (OM), which has been shown to increase the power output of the cardiac muscle and is currently in clinical trials for the treatment of heart failure. While the overall effect of OM on the mechano-chemical cycle of myosin is to increase the fraction of myosin molecules in the sarcomere that are strongly bound to actin, the molecular basis of its action is still not completely clear. We present here a Molecular Dynamics study of the motor domain of human cardiac myosin bound to OM, where the effects of the drug on the dynamical properties of the protein are investigated for the first time with atomistic resolution. We found that OM has a double effect on myosin dynamics, inducing a) an increased coupling of the motions of the converter and lever arm subdomains to the rest of the protein and b) a rewiring of the network of dynamic correlations, which produces preferential communication pathways between the OM binding site and distant functional regions. The location of the residues responsible for these effects suggests possible strategies for the future development of improved drugs and the targeting of specific cardiomyopathy-related mutations. Author summaryCardiac myosin is a motor protein responsible for the contraction of the heart muscle. New strategies for the cure of heart diseases are currently being developed by using myosin modulators, which are small molecules that can interact with myosin and modify its activity. The advantage of this approach over traditional drugs is that by directly targeting cardiac myosin it is possible to have drugs with reduced side effects. Moreover, the availability of a spectrum of molecules to finely tune myosin to a desired level of activity opens the possibility to develop more precise and personalised drug therapies. In this work, we study a recently discovered activator of cardiac myosin, omecamtiv mecarbil, in order to understand its mechanism of action. In particular, we use Molecular Dynamics simulations to unravel the effects of the drug on myosin motions, which are closely related to its PLOS Computational Biology | https://doi

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“…dADP binding stabilizes a myosin conformation that is more energetically favorable for actin binding (closed cleft conformation), resulting in more exposed polar residues on the actin binding surface of myosin, thus increasing the probability of electrostatic interactions between actin and myosin (Figure 4b). MD simulation results were supported by motility assays, which indicated dATP enhances weak binding electrostatic interactions between actin and myosin(33). These studies suggest the missing hydroxyl group in dATP modifies myosin head structure in a manner resulting in an increased rate and affinity of actin binding, and explain the previously observed increase in cross-bridge cycling (Figure 4c)(34).…”

Section: Datp Mechanism Of Actionmentioning

confidence: 95%

“…(B) Representative actin binding surface structures on myosin (circled area on ribbon structure) with ADP and dADP simulations at 50ns, showing conformational changes in myosin resulting in increased exposure of polar residues (green regions) in the actin binding surface with dADP binding. Modeling figures adapted from Nowakowski (in review)(33). (C) Schematic illustrating the chemo-mechanical cycle of muscle contraction.…”

Section: Figurementioning

confidence: 99%

Translation of Cardiac Myosin Activation With 2-Deoxy-ATP to Treat Heart Failure Via an Experimental Ribonucleotide Reductase-Based Gene Therapy

Thomson

Odom

Murry³

et al. 2016

JACC: Basic to Translational Science

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SummaryDespite recent advances, chronic heart failure remains a significant and growing unmet medical need, reaching epidemic proportions carrying substantial morbidity, mortality, and costs. A safe and convenient therapeutic agent that produces sustained inotropic effects could ameliorate symptoms and improve functional capacity and quality of life. The authors discovered that small amounts of 2-deoxy-ATP (dATP) activate cardiac myosin leading to enhanced contractility in normal and failing heart muscle. Cardiac myosin activation triggers faster myosin cross-bridge cycling with greater force generation during each contraction. They describe the rationale and results of a translational medicine effort to increase dATP levels using a gene therapy strategy that up-regulates ribonucleotide reductase, the rate-limiting enzyme for dATP synthesis, selectively in cardiomyocytes. In small and large animal models of heart failure, a single dose of this gene therapy has led to sustained inotropic effects with no toxicity or safety concerns identified to date. Further animal studies are being conducted with the goal of testing this agent in patients with heart failure.

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Molecular mechanisms underlying deoxy‐ADP.Pi activation of pre‐powerstroke myosin

Cited by 14 publications

References 62 publications

Cardiac myosin activation with 2-deoxy-ATP via increased electrostatic interactions with actin

Cardiac myosin activation with 2-deoxy-ATP via increased electrostatic interactions with actin

Allosteric Modulation of Cardiac Myosin Dynamics by Omecamtiv Mecarbil

Translation of Cardiac Myosin Activation With 2-Deoxy-ATP to Treat Heart Failure Via an Experimental Ribonucleotide Reductase-Based Gene Therapy

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