Intensity Fluctuation Autocorrelation Studies of the Dynamics of Muscular Contraction

Carlson, Francis D.; Fraser, Allan B.

doi:10.1007/978-1-4615-8906-8_15

Cited by 6 publications

(6 citation statements)

References 5 publications

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“…Close in size is the heavy meromyosin subfragment 2 (SF2) with dimensions of 60X2 nm (Lowey et al, 1967). The hydrodynamic diameter of the SF2 was found by the PCS method to be 10.8 nm (Carlson and Fraser, 1974), which is close to our 8.8 nm Dav value for MLCK monomer (Table 1). Ausio et al (1992) did not observe MLCK oligomers because their investigations were carried out at higher ionic strength conditions (0.2 M NaCl) together with additional high sucrose concentrations present.…”

Section: Discussion Mlck Oligomeric Suprastructuresupporting

confidence: 88%

Smooth muscle myosin light chain kinase, supramolecular organization, modulation of activity, and related conformational changes

Filenko

Danilova

Sobieszek

1997

Biophysical Journal

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It has recently been suggested that activation of smooth muscle myosin light chain kinase (MLCK) can be modulated by formation of supramolecular structures (Sobieszek, A. 1991. Regulation of smooth muscle myosin light chain kinase. Allosteric effects and co-operative activation by CaM. J. Mol. Biol. 220:947-957). The present light scattering data demonstrate that the inactive (calmodulin-free) MLCK apoenzyme exists in solution as a mixture of oligomeric (2% by weight), dimeric (53%), and monomeric (45%) species at physiological ionic strength (160 mM salt). These long-living assemblies, the lifetime of which was measured by minutes, were in equilibrium with each other. The most likely form of the oligomer was a spiral-like hexamer, the dimensions of which fit very well the helical structure of self-assembled myosin filaments (Sobieszek, A. 1972. Cross-bridges on self-assembled smooth muscle myosin filaments. J. Mol. Biol. 70:741-744). After activation of the kinase by calmodulin (CaM) we could not detect any appreciable changes in the distribution of the kinase species either when the kinase was saturated with CaM or when its molar concentration exceeded that of CaM. Our fluorescent measurements suggest that the earlier observed inhibition of kinase at substoichiometric amounts of CaM (Sobieszek, A., A. Strobl, B. Ortner, and E. Babiychuk. 1993. Ca2+-calmodulin-dependent modification of smooth-muscle myosin light chain kinase leading to its co-operative activation by calmodulin. Biochem. J. 295:405-411) is associated with slow conformational change(s) of the activated (CaM-bound) kinase molecules. Such conformational rearrangements also took place with equimolar kinase to CaM; however, in this case there was no decrease in MLCK activity. The nature of these conformational changes, which are accompanied by reduction of the kinase for CaM affinity, is discussed.

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Section: Discussion Mlck Oligomeric Suprastructuresupporting

confidence: 88%

Smooth muscle myosin light chain kinase, supramolecular organization, modulation of activity, and related conformational changes

Filenko

Danilova

Sobieszek

1997

Biophysical Journal

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“…These experimental findings are incompatible with the hypotheses that: (a) the only structural elements in muscle that move during a steady state of contraction are the myosin cross bridges, and (b) the axial forces acting across or possibly within a single myofibrillar sarcomere are in exact balance at every instant during the steady state. A preliminary report of these results was given by Carlson and Fraser (1974).…”

Section: Introductionmentioning

confidence: 95%

Structural dynamics of frog muscle during isometric contraction.

Bonner¹,

Carlson²

1975

The Journal of General Physiology

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Intensity fluctuation autocorrelation functions of laser light scattered by actively contracting muscle were measured at points in the scattered field. They were reproducible and showed characteristics which depended on the physiological state of the muscle and the parameters of the scattering geometry. The autocorrelation functions had large amplitudes and decay rates that varied significantly with the phase of the contraction-relaxation cycle. The dependence of the autocorrelation function on scattering geometry indicated many elements with diameters on the order of 0.5 #m (presumed to be myofibriUar sarcomeres or their A bands or I bands) undergo independent random changes in their axial positions and their internal distribution of optical polarizability during the plateau of an isometric tetanus. The experimental results are interpreted in terms of a model in which most of the scattering elements in isometrically contracting muscle have random fluctuating axial velocities of average magnitude 20 nm/ms that persist for a few milliseconds at least. In addition to these axial motions there are local fluctuations in polarizability. Similar intensity fluctuation autocorrelation functions were observed throughout the active state on two muscle preparations, whole sartorius muscle and Small bundles of single fibers (three to eight) of semitendinosus muscle. These results imply that the tension developed during an isometric tetanus contains a fluctuating component as well as a constant component.

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“…Close by dimentions (60 * 2 nm) is myosin subfragment-2 (SF2) [20]. SF2 hydrodynamic diameter was found by the LCS method to be of 10.8 nm [21 ]. Accor dingly, we identified particles with D av = 7.5 nm in 6-9 nm interval ( Fig.…”

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confidence: 72%

Detection and characterization of protein oligomeric species by light scattering methods: myosin light chain kinase supramolecular structures

Filenko

2000

Biopolym. Cell

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Modem multi-angle light scattering, fast protein liquid chromatography and laser correlation spectroscopy used together give rather complete information about the distribution of different protein particles in solution and their characteristics. The data received by these methods on smooth muscle myosin light chain kinase (MLCK) as the object of investigation suggest that MLCK exists in solution as a mixture of oligomeric, dimeric and monomeric particles which contents at ionic strength close to physiological constitute 2 y 53 and 45 wt. % correspondingly. An important point is that supramolecular kinase species content in eluate from a gel filtration column was much higher than their content at equilibrium. The contributions of oligomer, dimer and monomer in eluate at the exit from the column were 5.3, 8J.5 and J 3.2 wt. % accordingly. All three kinase species are characterized by prolonged lifetime. The transition from pure dimer into equilibrium state lasts for about 10 min. The kinase dimer is a rod-like structure with molecular mass of about 2-Ю 5 kDa and root mean square (RMS) radius Rg 22 nm. Oligomer is characterized by RMS radius Rg 80 nm. Its structure may be presented as a helical ring containing 10 kinase molecules per turn with a number of turns about 10. Another more realistic explanation of the data obtained involves a rod-like or elongated spiral model according to which 6 kinase molecules, arranged in line or elongated spiral, form one structural unit, which must be a real oligomer (hexamer). About 17 such structural units, associated in parallel, form aggregates with molecular mass of about 10 1 kDa. Kinase spiral hexamer fits well the structure of smooth myosin filament with which the kinase is in close contact in vivo. Preliminary experiments with a number of other proteins (myosin, myosin subfragment 1, bovine serum albumin, chemotrypsin, papain) showed that all of them form supramolecular structures with prolonged time of transition from pure species to equilibrium distribution of monomers and supramolecular structures.

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Intensity Fluctuation Autocorrelation Studies of the Dynamics of Muscular Contraction

Cited by 6 publications

References 5 publications

Smooth muscle myosin light chain kinase, supramolecular organization, modulation of activity, and related conformational changes

Smooth muscle myosin light chain kinase, supramolecular organization, modulation of activity, and related conformational changes

Structural dynamics of frog muscle during isometric contraction.

Detection and characterization of protein oligomeric species by light scattering methods: myosin light chain kinase supramolecular structures

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