Myosin S1 changes the orientation of caldesmon on actin

Danuta Szczesna-Cordary, Philip Graceffa, C. L. Albert Wang, Sherwin S. Lehrer

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Changes in the orientation of caldesmon bound to actin in skeletal ghost myofibrils caused by the binding of myosin subfragment 1 (S1) were measured by fluorescence-detected linear dichroism using fluorescence microscopy. Gizzard caldesmon, labeled with acrylodan at its two Cys residues (CaD*), bound to actin with a probe angle that was unaffected by actin-bound tropomyosin. Irrigation of fibrils with myosin S1 dissociated most of the bound CaD*, but reintroduction of CaD* resulted in its rebinding to actin, without dissociation of S1, with a 7° difference in probe angle. A similar change in probe angle was also observed when a 27-kDa actin-binding C-terminal fragment of caldesmon, labeled with acrylodan at its single Cys 580 (CaD-27*), was used. Introducing MgADP, which bound to S1 in the CaD*-actin-S1 ternary complex in the fibril, reversed the bound CaD* dichroism. These results indicate that (i) myosin heads and caldesmon compete for a common actin binding site; (ii) a ternary complex of CaD*-actin-S1 can be formed with an orientation of CaD* different from that in the CaD*-actin binary complex, and (iii) MgADP, which binds to and reorients myosin S1, affects the orientation of CaD* in the ternary complex. These results are consistent with a two-state binding model of caldesmon for actin in which state 1 involves a site that is competitive with S1 binding and state 2 involves a site that is formed in the presence of bound S1.

Original languageEnglish
Pages (from-to)6716-6720
Number of pages5
JournalBiochemistry®
StatePublished - Dec 1 1994
Externally publishedYes

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Calmodulin-Binding Proteins
Myosin Subfragments
Actins
Adenosine Diphosphate
Tropomyosin
Myofibrils
Fluorescence microscopy
Myosins
Fluorescence Microscopy
Irrigation
Fluorescence
Binding Sites

ASJC Scopus subject areas

  • Biochemistry

Cite this

Szczesna-Cordary, D., Graceffa, P., Albert Wang, C. L., & Lehrer, S. S. (1994). Myosin S1 changes the orientation of caldesmon on actin. Biochemistry®, 6716-6720.

Myosin S1 changes the orientation of caldesmon on actin. / Szczesna-Cordary, Danuta; Graceffa, Philip; Albert Wang, C. L.; Lehrer, Sherwin S.

In: Biochemistry®, 01.12.1994, p. 6716-6720.

Research output: Contribution to journalArticle

Szczesna-Cordary, D, Graceffa, P, Albert Wang, CL & Lehrer, SS 1994, 'Myosin S1 changes the orientation of caldesmon on actin', Biochemistry®, pp. 6716-6720.
Szczesna-Cordary D, Graceffa P, Albert Wang CL, Lehrer SS. Myosin S1 changes the orientation of caldesmon on actin. Biochemistry®. 1994 Dec 1;6716-6720.
Szczesna-Cordary, Danuta ; Graceffa, Philip ; Albert Wang, C. L. ; Lehrer, Sherwin S. / Myosin S1 changes the orientation of caldesmon on actin. In: Biochemistry®. 1994 ; pp. 6716-6720.
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