The actin-binding cleft: functional characterisation of myosin II with a strut mutation
- 119 Downloads
The myosin cross-bridge has two essential properties: to undergo the “power stroke” and to bind and release from actin – both under control of ATP binding and hydrolysis. In the absence of ATP the cross-bridge binds to actin with high affinity: the binding of ATP causes rapid release of the cross-bridge from actin. The actin binding-site is split by a deep cleft that closes on strong binding to actin. The cleft is straddled by a short polypeptide known as the “strut”. In the following we summarise the structural basis of the power stroke and the control of actin affinity and then present data on the effects on actin affinity of replacing the strut by a flexible linker.
KeywordsActin Binding Power Stroke Myosin Versus Dictyostelium Myosin Myosin Motor Domain
We are grateful to Prof D. Manstein and to Prof M. Geeves for helpful discussions. This work was supported by the Grant HO 481/16-1 from the Deutsche Forschungsgemeinschaft as part of the Schwerpunktprogram “Molecular Motors”. T.F.R. gratefully acknowledges support by a Peter und Traudl Engelhorn Stiftung postdoctoral fellowship. The following programs have been used in preparing the figures: BobScript v2.6 (Esnouf, 1997, 1999); Molscript (Kraulis, 1991); Raster 3D (Merritt and Bacon, 1997).
- Esnouf RM (1997) An extensively modified version of MolScript that includes greatly enhanced coloring capabilities. J Mol Graph Model 15: 132–134, 112–113Google Scholar
- Geeves M and Holmes K (2005) The molecular mechanism of muscle contraction. Adv Protein Chem 79:161–193Google Scholar
- Geeves MA (1992) The actomyosin ATPase: a two-state system. Philos Trans R Soc Lond B Biol Sci 336: 63–70; discussion 70–71Google Scholar