Title

Blebbistatin stabilizes the helical order of myosin filaments by promoting the switch 2 closed state

UMMS Affiliation

Department of Cell Biology

Date

7-5-2008

Document Type

Article

Subjects

Actins; Adenosine Diphosphate; Animals; Apyrase; Arachnida; Heterocyclic Compounds with 4 or More Rings; Muscles; Myosins; Phosphates; Protein Binding

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

Blebbistatin is a small-molecule, high-affinity, noncompetitive inhibitor of myosin II. We have used negative staining electron microscopy to study the effects of blebbistatin on the organization of the myosin heads on muscle thick filaments. Loss of ADP and Pi from the heads causes thick filaments to lose their helical ordering. In the presence of 100 microM blebbistatin, disordering was at least 10 times slower. In the M.ADP state, myosin heads are also disordered. When blebbistatin was added to M.ADP thick filaments, helical ordering was restored. However, blebbistatin did not improve the order of thick filaments lacking bound nucleotide. Addition of calcium to relaxed muscle homogenates induced thick-thin filament interaction and filament sliding. In the presence of blebbistatin, filament interaction was inhibited. These structural observations support the conclusion, based on biochemical studies, that blebbistatin inhibits myosin ATPase and actin interaction by stabilizing the closed switch 2 structure of the myosin head. These properties make blebbistatin a useful tool in structural and functional studies of cell motility and muscle contraction.

Rights and Permissions

Citation: Biophys J. 2008 Oct;95(7):3322-9. Epub 2008 Jul 3. Link to article on publisher's site

DOI of Published Version

10.1529/biophysj.108.137067

Related Resources

Link to Article in PubMed

Journal Title

Biophysical journal

PubMed ID

18599626