Abstract
Purified smooth muscle myosin in the in vitro motility assay propels actin filaments at 1/10 the velocity, yet produces 3-4 times more force than skeletal muscle myosin. At the level of a single myosin molecule, these differences in force and actin filament velocity may be reflected in the size and duration of single motion and force-generating events, or in the kinetics of the cross-bridge cycle. Specifically, an increase in either unitary force or duty cycle may explain the enhanced force-generating capacity of smooth muscle myosin. Similarly, an increase in attached time or decrease in unitary displacement may explain the reduced actin filament velocity of smooth muscle myosin. To discriminate between these possibilities, we used a laser trap to measure unitary forces and displacements from single smooth and skeletal muscle myosin molecules. We analyzed our data using mean-variance analysis, which does not rely on scoring individual events by eye, and emphasizes periods in the data with constant properties. Both myosins demonstrated multiple but similar event populations with discrete peaks at approximately +11 and -11 nm in displacement, and 1.5 and 3.5 pN in force. Mean attached times for smooth muscle myosin were longer than for skeletal-muscle myosin. These results explain much of the difference in actin filament velocity between these myosins, and suggest that an increased duty cycle is responsible for the enhanced force-generating capacity of smooth over skeletal-muscle myosin.
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- Babij P., Kelly C., Periasamy M. Characterization of a mammalian smooth muscle myosin heavy-chain gene: complete nucleotide and protein coding sequence and analysis of the 5' end of the gene. Proc Natl Acad Sci U S A. 1991 Dec 1;88(23):10676–10680. doi: 10.1073/pnas.88.23.10676. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Block S. M. Macromolecular physiology. One small step for myosin... Nature. 1995 Nov 9;378(6553):132–133. doi: 10.1038/378132a0. [DOI] [PubMed] [Google Scholar]
- Block S. M., Svoboda K. Analysis of high resolution recordings of motor movement. Biophys J. 1995 Apr;68(4 Suppl):230S–241S. [PMC free article] [PubMed] [Google Scholar]
- Brenner B., Chalovich J. M., Yu L. C. Distinct molecular processes associated with isometric force generation and rapid tension recovery after quick release. Biophys J. 1995 Apr;68(4 Suppl):106S–111S. [PMC free article] [PubMed] [Google Scholar]
- Finer J. T., Mehta A. D., Spudich J. A. Characterization of single actin-myosin interactions. Biophys J. 1995 Apr;68(4 Suppl):291S–297S. [PMC free article] [PubMed] [Google Scholar]
- Finer J. T., Simmons R. M., Spudich J. A. Single myosin molecule mechanics: piconewton forces and nanometre steps. Nature. 1994 Mar 10;368(6467):113–119. doi: 10.1038/368113a0. [DOI] [PubMed] [Google Scholar]
- HUXLEY A. F. Muscle structure and theories of contraction. Prog Biophys Biophys Chem. 1957;7:255–318. [PubMed] [Google Scholar]
- Harada Y., Noguchi A., Kishino A., Yanagida T. Sliding movement of single actin filaments on one-headed myosin filaments. Nature. 1987 Apr 23;326(6115):805–808. doi: 10.1038/326805a0. [DOI] [PubMed] [Google Scholar]
- Harris D. E., Warshaw D. M. Smooth and skeletal muscle actin are mechanically indistinguishable in the in vitro motility assay. Circ Res. 1993 Jan;72(1):219–224. doi: 10.1161/01.res.72.1.219. [DOI] [PubMed] [Google Scholar]
- Harris D. E., Warshaw D. M. Smooth and skeletal muscle myosin both exhibit low duty cycles at zero load in vitro. J Biol Chem. 1993 Jul 15;268(20):14764–14768. [PubMed] [Google Scholar]
- Harris D. E., Work S. S., Wright R. K., Alpert N. R., Warshaw D. M. Smooth, cardiac and skeletal muscle myosin force and motion generation assessed by cross-bridge mechanical interactions in vitro. J Muscle Res Cell Motil. 1994 Feb;15(1):11–19. doi: 10.1007/BF00123828. [DOI] [PubMed] [Google Scholar]
- Huxley H. E. Sliding filaments and molecular motile systems. J Biol Chem. 1990 May 25;265(15):8347–8350. [PubMed] [Google Scholar]
- Ishijima A., Harada Y., Kojima H., Funatsu T., Higuchi H., Yanagida T. Single-molecule analysis of the actomyosin motor using nano-manipulation. Biochem Biophys Res Commun. 1994 Mar 15;199(2):1057–1063. doi: 10.1006/bbrc.1994.1336. [DOI] [PubMed] [Google Scholar]
- Kawai M., Zhao Y. Cross-bridge scheme and force per cross-bridge state in skinned rabbit psoas muscle fibers. Biophys J. 1993 Aug;65(2):638–651. doi: 10.1016/S0006-3495(93)81109-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kron S. J., Spudich J. A. Fluorescent actin filaments move on myosin fixed to a glass surface. Proc Natl Acad Sci U S A. 1986 Sep;83(17):6272–6276. doi: 10.1073/pnas.83.17.6272. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Marston S. B., Taylor E. W. Comparison of the myosin and actomyosin ATPase mechanisms of the four types of vertebrate muscles. J Mol Biol. 1980 Jun 5;139(4):573–600. doi: 10.1016/0022-2836(80)90050-9. [DOI] [PubMed] [Google Scholar]
- Miyata H., Hakozaki H., Yoshikawa H., Suzuki N., Kinosita K., Jr, Nishizaka T., Ishiwata S. Stepwise motion of an actin filament over a small number of heavy meromyosin molecules is revealed in an in vitro motility assay. J Biochem. 1994 Apr;115(4):644–647. doi: 10.1093/oxfordjournals.jbchem.a124389. [DOI] [PubMed] [Google Scholar]
- Molloy J. E., Burns J. E., Kendrick-Jones J., Tregear R. T., White D. C. Movement and force produced by a single myosin head. Nature. 1995 Nov 9;378(6553):209–212. doi: 10.1038/378209a0. [DOI] [PubMed] [Google Scholar]
- Molloy J. E., Burns J. E., Sparrow J. C., Tregear R. T., Kendrick-Jones J., White D. C. Single-molecule mechanics of heavy meromyosin and S1 interacting with rabbit or Drosophila actins using optical tweezers. Biophys J. 1995 Apr;68(4 Suppl):298S–305S. [PMC free article] [PubMed] [Google Scholar]
- Murphy R. A., Herlihy J. T., Megerman J. Force-generating capacity and contractile protein content of arterial smooth muscle. J Gen Physiol. 1974 Dec;64(6):691–705. doi: 10.1085/jgp.64.6.691. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Onishi H., Fujiwara K. The rigor configuration of smooth muscle heavy meromyosin trapped by a zero-length cross-linker. Biochemistry. 1990 Mar 27;29(12):3013–3023. doi: 10.1021/bi00464a018. [DOI] [PubMed] [Google Scholar]
- Onishi H., Maita T., Matsuda G., Fujiwara K. Lys-65 and Glu-168 are the residues for carbodiimide-catalyzed cross-linking between the two heads of rigor smooth muscle heavy meromyosin. J Biol Chem. 1990 Nov 5;265(31):19362–19368. [PubMed] [Google Scholar]
- Pardee J. D., Spudich J. A. Purification of muscle actin. Methods Enzymol. 1982;85(Pt B):164–181. doi: 10.1016/0076-6879(82)85020-9. [DOI] [PubMed] [Google Scholar]
- Patlak J. B. Measuring kinetics of complex single ion channel data using mean-variance histograms. Biophys J. 1993 Jul;65(1):29–42. doi: 10.1016/S0006-3495(93)81041-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Patlak J. B., Ortiz M. Kinetic diversity of Na+ channel bursts in frog skeletal muscle. J Gen Physiol. 1989 Aug;94(2):279–301. doi: 10.1085/jgp.94.2.279. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Peskin C. S., Oster G. Coordinated hydrolysis explains the mechanical behavior of kinesin. Biophys J. 1995 Apr;68(4 Suppl):202S–211S. [PMC free article] [PubMed] [Google Scholar]
- Rayment I., Rypniewski W. R., Schmidt-Bäse K., Smith R., Tomchick D. R., Benning M. M., Winkelmann D. A., Wesenberg G., Holden H. M. Three-dimensional structure of myosin subfragment-1: a molecular motor. Science. 1993 Jul 2;261(5117):50–58. doi: 10.1126/science.8316857. [DOI] [PubMed] [Google Scholar]
- Rovner A. S., Freyzon Y., Trybus K. M. Chimeric substitutions of the actin-binding loop activate dephosphorylated but not phosphorylated smooth muscle heavy meromyosin. J Biol Chem. 1995 Dec 22;270(51):30260–30263. doi: 10.1074/jbc.270.51.30260. [DOI] [PubMed] [Google Scholar]
- Siemankowski R. F., Wiseman M. O., White H. D. ADP dissociation from actomyosin subfragment 1 is sufficiently slow to limit the unloaded shortening velocity in vertebrate muscle. Proc Natl Acad Sci U S A. 1985 Feb;82(3):658–662. doi: 10.1073/pnas.82.3.658. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Simmons R. M., Finer J. T., Chu S., Spudich J. A. Quantitative measurements of force and displacement using an optical trap. Biophys J. 1996 Apr;70(4):1813–1822. doi: 10.1016/S0006-3495(96)79746-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Spudich J. A. How molecular motors work. Nature. 1994 Dec 8;372(6506):515–518. doi: 10.1038/372515a0. [DOI] [PubMed] [Google Scholar]
- Svoboda K., Block S. M. Biological applications of optical forces. Annu Rev Biophys Biomol Struct. 1994;23:247–285. doi: 10.1146/annurev.bb.23.060194.001335. [DOI] [PubMed] [Google Scholar]
- Toyoshima Y. Y., Kron S. J., McNally E. M., Niebling K. R., Toyoshima C., Spudich J. A. Myosin subfragment-1 is sufficient to move actin filaments in vitro. Nature. 1987 Aug 6;328(6130):536–539. doi: 10.1038/328536a0. [DOI] [PubMed] [Google Scholar]
- Uyeda T. Q., Abramson P. D., Spudich J. A. The neck region of the myosin motor domain acts as a lever arm to generate movement. Proc Natl Acad Sci U S A. 1996 Apr 30;93(9):4459–4464. doi: 10.1073/pnas.93.9.4459. [DOI] [PMC free article] [PubMed] [Google Scholar]
- VanBuren P., Waller G. S., Harris D. E., Trybus K. M., Warshaw D. M., Lowey S. The essential light chain is required for full force production by skeletal muscle myosin. Proc Natl Acad Sci U S A. 1994 Dec 20;91(26):12403–12407. doi: 10.1073/pnas.91.26.12403. [DOI] [PMC free article] [PubMed] [Google Scholar]
- VanBuren P., Work S. S., Warshaw D. M. Enhanced force generation by smooth muscle myosin in vitro. Proc Natl Acad Sci U S A. 1994 Jan 4;91(1):202–205. doi: 10.1073/pnas.91.1.202. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Warshaw D. M., Desrosiers J. M., Work S. S., Trybus K. M. Smooth muscle myosin cross-bridge interactions modulate actin filament sliding velocity in vitro. J Cell Biol. 1990 Aug;111(2):453–463. doi: 10.1083/jcb.111.2.453. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Warshaw D. M., Fay F. S. Cross-bridge elasticity in single smooth muscle cells. J Gen Physiol. 1983 Aug;82(2):157–199. doi: 10.1085/jgp.82.2.157. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Warshaw D. M. Force: velocity relationship in single isolated toad stomach smooth muscle cells. J Gen Physiol. 1987 May;89(5):771–789. doi: 10.1085/jgp.89.5.771. [DOI] [PMC free article] [PubMed] [Google Scholar]
- White S., Martin A. F., Periasamy M. Identification of a novel smooth muscle myosin heavy chain cDNA: isoform diversity in the S1 head region. Am J Physiol. 1993 May;264(5 Pt 1):C1252–C1258. doi: 10.1152/ajpcell.1993.264.5.C1252. [DOI] [PubMed] [Google Scholar]
- Yamakawa M., Harris D. E., Fay F. S., Warshaw D. M. Mechanical transients of single toad stomach smooth muscle cells. Effects of lowering temperature and extracellular calcium. J Gen Physiol. 1990 Apr;95(4):697–715. doi: 10.1085/jgp.95.4.697. [DOI] [PMC free article] [PubMed] [Google Scholar]






