Myosin and tropomyosin stabilize the conformation of formin-nucleated actin filaments

Zoltán Ujfalusi, M. Kovács, Nikolett T. Nagy, Szilvia Barkó, G. Hild, András Lukács, M. Nyitrai, B. Bugyi

Research output: Contribution to journalArticle

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Abstract

The conformational elasticity of the actin cytoskeleton is essential for its versatile biological functions. Increasing evidence supports that the interplay between the structural and functional properties of actin filaments is finely regulated by actin-binding proteins; however, the underlying mechanisms and biological consequences are not completely understood. Previous studies showed that the binding of formins to the barbed end induces conformational transitions in actin filaments by making them more flexible through long range allosteric interactions. These conformational changes are accompanied by altered functional properties of the filaments. To get insight into the conformational regulation of formin-nucleated actin structures, in the present work we investigated in detail how binding partners of formin-generated actin structures, myosin and tropomyosin, affect the conformation of the formin-nucleated actin filaments using fluorescence spectroscopic approaches. Timedependent fluorescence anisotropy and temperature-dependent Förster-type resonance energy transfer measurements revealed that heavy meromyosin, similarly to tropomyosin, restores the formin-induced effects and stabilizes the conformation of actin filaments. The stabilizing effect of heavy meromyosin is cooperative. The kinetic analysis revealed that despite the qualitatively similar effects of heavy meromyosin and tropomyosin on the conformational dynamics of actin filaments the mechanisms of the conformational transition are different for the two proteins. Heavy meromyosin stabilizes the formin-nucleated actin filaments in an apparently single step reaction upon binding, whereas the stabilization by tropomyosin occurs after complex formation. These observations support the idea that actin-binding proteins are key elements of the molecular mechanisms that regulate the conformational and functional diversity of actin filaments in living cells.

Original languageEnglish
Pages (from-to)31894-31904
Number of pages11
JournalJournal of Biological Chemistry
Volume287
Issue number38
DOIs
Publication statusPublished - Sep 14 2012

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Tropomyosin
Myosins
Actin Cytoskeleton
Conformations
Actins
Myosin Subfragments
Microfilament Proteins
Fluorescence Polarization
Fluorescence
Energy Transfer
Elasticity
Energy transfer
Anisotropy
Stabilization
Temperature
Cells

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

Myosin and tropomyosin stabilize the conformation of formin-nucleated actin filaments. / Ujfalusi, Zoltán; Kovács, M.; Nagy, Nikolett T.; Barkó, Szilvia; Hild, G.; Lukács, András; Nyitrai, M.; Bugyi, B.

In: Journal of Biological Chemistry, Vol. 287, No. 38, 14.09.2012, p. 31894-31904.

Research output: Contribution to journalArticle

Ujfalusi, Zoltán ; Kovács, M. ; Nagy, Nikolett T. ; Barkó, Szilvia ; Hild, G. ; Lukács, András ; Nyitrai, M. ; Bugyi, B. / Myosin and tropomyosin stabilize the conformation of formin-nucleated actin filaments. In: Journal of Biological Chemistry. 2012 ; Vol. 287, No. 38. pp. 31894-31904.
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