Biophysical Journal 72: 2398-2404 (1997)
© 1997 the Biophysical Society

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hodgkinson, J L Articles by Lehman, W Search for Related Content PubMed PubMed Citation Articles by Hodgkinson, J L Articles by Lehman, W

Three-dimensional image reconstruction of reconstituted smooth muscle thin filaments: effects of caldesmon.

Imperial College School of Medicine, National Heart and Lung Institute, London, United Kingdom. julie.hodgkinson@ic.ac.uk

ABSTRACT

Caldesmon inhibits actomyosin ATPase and filament sliding in vitro, and therefore may play a role in modulating smooth and non-muscle motile activities. A bacterially expressed caldesmon fragment, 606C, which consists of the C-terminal 150 amino acids of the intact molecule, possesses the same inhibitory properties as full-length caldesmon and was used in our structural studies to examine caldesmon function. Three-dimensional image reconstruction was carried out from electron micrographs of negatively stained, reconstituted thin filaments consisting of actin and smooth muscle tropomyosin both with and without added 606C. Helically arranged actin monomers and tropomyosin strands were observed in both cases. In the absence of 606C, tropomyosin adopted a position on the inner edge of the outer domain of actin monomers, with an apparent connection to sub-domain 1 of actin. In 606C-containing filaments that inhibited acto-HMM ATPase activity, tropomyosin was found in a different position, in association with the inner domain of actin, away from the majority of strong myosin binding sites. The effect of caldesmon on tropomyosin position therefore differs from that of troponin on skeletal muscle filaments, implying that caldesmon and troponin act by different structural mechanisms.

This article has been cited by other articles:

				R. Maytum, V. Hatch, M. Konrad, W. Lehman, and M. A. Geeves Ultra Short Yeast Tropomyosins Show Novel Myosin Regulation J. Biol. Chem., January 25, 2008; 283(4): 1902 - 1910. [Abstract] [Full Text] [PDF]

				S. Ansari, M. Alahyan, S. B. Marston, and M. EL-Mezgueldi Role of Caldesmon in the Ca2+ Regulation of Smooth Muscle Thin Filaments: EVIDENCE FOR A COOPERATIVE SWITCHING MECHANISM J. Biol. Chem., January 4, 2008; 283(1): 47 - 56. [Abstract] [Full Text] [PDF]

				S. Somara and K. N. Bitar Phosphorylated HSP27 modulates the association of phosphorylated caldesmon with tropomyosin in colonic smooth muscle Am J Physiol Gastrointest Liver Physiol, October 1, 2006; 291(4): G630 - G639. [Abstract] [Full Text] [PDF]

				M. Alahyan, M. R. Webb, S. B. Marston, and M. EL-Mezgueldi The Mechanism of Smooth Muscle Caldesmon-Tropomyosin Inhibition of the Elementary Steps of the Actomyosin ATPase J. Biol. Chem., July 14, 2006; 281(28): 19433 - 19448. [Abstract] [Full Text] [PDF]

				P. Graceffa and A. Mazurkie Effect of Caldesmon on the Position and Myosin-induced Movement of Smooth Muscle Tropomyosin Bound to Actin J. Biol. Chem., February 11, 2005; 280(6): 4135 - 4143. [Abstract] [Full Text] [PDF]

				D. B. Foster, R. Huang, V. Hatch, R. Craig, P. Graceffa, W. Lehman, and C.-L. A. Wang Modes of Caldesmon Binding to Actin: SITES OF CALDESMON CONTACT AND MODULATION OF INTERACTIONS BY PHOSPHORYLATION J. Biol. Chem., December 17, 2004; 279(51): 53387 - 53394. [Abstract] [Full Text] [PDF]

				S. Somara and K. N. Bitar Tropomyosin interacts with phosphorylated HSP27 in agonist-induced contraction of smooth muscle Am J Physiol Cell Physiol, June 1, 2004; 286(6): C1290 - C1301. [Abstract] [Full Text] [PDF]

				D. A. Smith, R. Maytum, and M. A. Geeves Cooperative Regulation of Myosin-Actin Interactions by a Continuous Flexible Chain I: Actin-Tropomyosin Systems Biophys. J., May 1, 2003; 84(5): 3155 - 3167. [Abstract] [Full Text] [PDF]

				A. M. Resetar, J. M. Stephens, and J. M. Chalovich Troponin-Tropomyosin: An Allosteric Switch or a Steric Blocker? Biophys. J., August 1, 2002; 83(2): 1039 - 1049. [Abstract] [Full Text] [PDF]

				D. M. Helfman, E. T. Levy, C. Berthier, M. Shtutman, D. Riveline, I. Grosheva, A. Lachish-Zalait, M. Elbaum, and A. D. Bershadsky Caldesmon Inhibits Nonmuscle Cell Contractility and Interferes with the Formation of Focal Adhesions Mol. Biol. Cell, October 1, 1999; 10(10): 3097 - 3112. [Abstract] [Full Text]

				K Okada, T Obinata, and H Abe XAIP1: a Xenopus homologue of yeast actin interacting protein 1 (AIP1), which induces disassembly of actin filaments cooperatively with ADF/cofilin family proteins J. Cell Sci., January 5, 1999; 112(10): 1553 - 1565. [Abstract] [PDF]

				J. M. Squire and E. P. Morris A new look at thin filament regulation in vertebrate skeletal muscle FASEB J, July 1, 1998; 12(10): 761 - 771. [Abstract] [Full Text]

				A. McGough, B. Pope, W. Chiu, and A. Weeds Cofilin Changes the Twist of F-Actin: Implications for Actin Filament Dynamics and Cellular Function J. Cell Biol., August 25, 1997; 138(4): 771 - 781. [Abstract] [Full Text] [PDF]

				V. Hatch, G. Zhi, L. Smith, J. T. Stull, R. Craig, and W. Lehman Myosin light chain kinase binding to a unique site on F-actin revealed by three-dimensional image reconstruction J. Cell Biol., August 6, 2001; 154(3): 611 - 618. [Abstract] [Full Text] [PDF]