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

Abstract

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 formore » 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.« less

Authors:

Powers, Joseph D.  ^[1];

• Search DOE PAGES for author "Powers, Joseph D."
• Search DOE PAGES for ORCID "0000-0001-7841-2337"

Yuan, Chen-Ching ^[2]; McCabe, Kimberly J. ^[3]; Murray, Jason D. ^[2]; Childers, Matthew Carter  ^[2];

• Search DOE PAGES for author "Childers, Matthew Carter"
• Search DOE PAGES for ORCID "0000-0003-2440-9612"

Flint, Galina V. ^[2]; Moussavi-Harami, Farid ^[2]; Mohran, Saffie ^[2]; Castillo, Romi ^[2]; Zuzek, Carla ^[2]; Ma, Weikang ^[4]; Daggett, Valerie ^[2]; McCulloch, Andrew D.  ^[3];

• Search DOE PAGES for author "McCulloch, Andrew D."
• Search DOE PAGES for ORCID "0000-0002-1708-5675"

Irving, Thomas C. ^[4]; Regnier, Michael ^[2]

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+ Show Author Affiliations

1. Univ. of Washington, Seattle, WA (United States); Univ. of California, San Diego, CA (United States)
2. Univ. of Washington, Seattle, WA (United States)
3. Univ. of California, San Diego, CA (United States)
4. Illinois Inst. of Technology, Chicago, IL (United States)

Publication Date:

Mon May 20 00:00:00 EDT 2019

Research Org.:

Argonne National Lab. (ANL), Argonne, IL (United States)

Sponsoring Org.:

National Institutes of Health (NIH)

OSTI Identifier:

1531016

Grant/Contract Number:  

AC02-06CH11357; NIH-T32-HL007312; NIH-T32-HL105373

Resource Type:

Accepted Manuscript

Journal Name:

Proceedings of the National Academy of Sciences of the United States of America

Additional Journal Information:

Journal Volume: 116; Journal Issue: 23; Journal ID: ISSN 0027-8424

Publisher:

National Academy of Sciences

Country of Publication:

United States

Language:

ENGLISH

Subject:

59 BASIC BIOLOGICAL SCIENCES; myosin structure; dATP; X-ray diffractions; arcomere structure; electrostatics