» Articles » PMID: 22404931

Three Distinct Actin-attached Structural States of Myosin in Muscle Fibers

Overview
Journal Biophys J
Publisher Cell Press
Specialty Biophysics
Date 2012 Mar 13
PMID 22404931
Citations 12
Authors
Affiliations
Soon will be listed here.
Abstract

We have used thiol cross-linking and electron paramagnetic resonance (EPR) to resolve structural transitions of myosin's light chain domain (LCD) and catalytic domain (CD) that are associated with force generation. Spin labels were incorporated into the LCD of muscle fibers by exchanging spin-labeled regulatory light chain for endogenous regulatory light chain, with full retention of function. To trap myosin in a structural state analogous to the elusive posthydrolysis ternary complex A.M'.D.P, we used pPDM to cross-link SH1 (Cys(707)) to SH2 (Cys(697)) on the CD. LCD orientation and dynamics were measured in three biochemical states: relaxation (A.M.T), SH1-SH2 cross-linked (A.M'.D.P analog), and rigor (A.M.D). EPR showed that the LCD of cross-linked fibers has an orientational distribution intermediate between relaxation and rigor, and saturation transfer EPR revealed slow rotational dynamics indistinguishable from that of rigor. Similar results were obtained for the CD using a bifunctional spin label to cross-link SH1-SH2, but the CD was more disordered than the LCD. We conclude that SH1-SH2 cross-linking traps a state in which both the CD and LCD are intermediate between relaxation (highly disordered and microsecond dynamics) and rigor (highly ordered and rigid), supporting the hypothesis that the cross-linked state is an A.M'D.P analog on the force generation pathway.

Citing Articles

A Highly Ordered Nitroxide Side Chain for Distance Mapping and Monitoring Slow Structural Fluctuations in Proteins.

Chen M, Kalai T, Cascio D, Bridges M, Whitelegge J, Elgeti M Appl Magn Reson. 2024; 55(1-3):251-277.

PMID: 38357006 PMC: 10861403. DOI: 10.1007/s00723-023-01618-8.


Actin-binding compounds, previously discovered by FRET-based high-throughput screening, differentially affect skeletal and cardiac muscle.

Guhathakurta P, Phung L, Prochniewicz E, Lichtenberger S, Wilson A, Thomas D J Biol Chem. 2020; 295(41):14100-14110.

PMID: 32788211 PMC: 7549046. DOI: 10.1074/jbc.RA120.014445.


Myosin and Other Energy-Transducing ATPases: Structural Dynamics Studied by Electron Paramagnetic Resonance.

Arata T Int J Mol Sci. 2020; 21(2).

PMID: 31968570 PMC: 7014194. DOI: 10.3390/ijms21020672.


Atomistic Models from Orientation and Distance Constraints Using EPR of a Bifunctional Spin Label.

Binder B, Thompson A, Thomas D Biophys J. 2019; 117(2):319-330.

PMID: 31301803 PMC: 6702148. DOI: 10.1016/j.bpj.2019.04.042.


Myosin lever arm orientation in muscle determined with high angular resolution using bifunctional spin labels.

Savich Y, Binder B, Thompson A, Thomas D J Gen Physiol. 2019; 151(8):1007-1016.

PMID: 31227551 PMC: 6683674. DOI: 10.1085/jgp.201812210.


References
1.
Walker M, Trinick J, White H . Millisecond time resolution electron cryo-microscopy of the M-ATP transient kinetic state of the acto-myosin ATPase. Biophys J. 1995; 68(4 Suppl):87S-91S. PMC: 1281881. View

2.
Hambly B, Franks K, Cooke R . Orientation of spin-labeled light chain-2 exchanged onto myosin cross-bridges in glycerinated muscle fibers. Biophys J. 1991; 59(1):127-38. PMC: 1281125. DOI: 10.1016/S0006-3495(91)82205-6. View

3.
Roopnarine O . Mechanical defects of muscle fibers with myosin light chain mutants that cause cardiomyopathy. Biophys J. 2003; 84(4):2440-9. PMC: 1302809. DOI: 10.1016/S0006-3495(03)75048-6. View

4.
Himmel D, Gourinath S, Reshetnikova L, Shen Y, Szent-Gyorgyi A, Cohen C . Crystallographic findings on the internally uncoupled and near-rigor states of myosin: further insights into the mechanics of the motor. Proc Natl Acad Sci U S A. 2002; 99(20):12645-50. PMC: 130514. DOI: 10.1073/pnas.202476799. View

5.
Nitao L, Reisler E . Probing the conformational states of the SH1-SH2 helix in myosin: a cross-linking approach. Biochemistry. 1998; 37(47):16704-10. DOI: 10.1021/bi9817212. View