Conformational change in actin filament induced by the interaction with heavy meromyosin: Effects of pH, tropomyosin and deoxy-ATP

Cardiac myosin from rats exercised 90 or 150 min daily for 8 wk was compared with the myosin from the hearts of matched sedentary controls. The Ca++-ATPase activity was increased 17 percent in rats exercised 90 min and 30 percent in rats exercised 150 min daily. In the exercised group 0.18 M KCl increased the myosin ATPase activity by 50 percent but had no effect in the control group. Ethylene glycol activated the Ca++-ATPase in control myosin preparations, but had no significant effect on myosin from conditioned hearts. Heavy meromyosin (HMM) from conditioned hearts had a higher Ca++-ATPase activity than from controls. Fluorescence with 8-anilinonaphthalene sulfonate (ANS) was increased 30 percent in HMM from conditioned hearts. The results suggest that the increased myosin ATPase activity in the hearts of exercised animals may be due to a local conformational change at or near the active site.

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The Synthesis of Kanamycin Analogs I. α-D-Glucopyranosyl Derivatives of Deoxystreptamine

Canadian Journal of Chemistry ◽

10.1139/v73-008 ◽

1973 ◽

Vol 51 (1) ◽

pp. 53-66 ◽

Cited By ~ 23

Author(s):

R. U. Lemieux ◽

T. L. Nagabhushan ◽

K. J. Clemetson ◽

L. C. N. Tucker

Keyword(s):

Conformational Change ◽

Ph Change ◽

Synthetic Compounds ◽

Effects Of Ph ◽

Derivatives Of

The procedure developed in this laboratory for the synthesis of α-D-glucopyranosides based on the reaction of dimeric tri-O-acetyl-2-deoxy-2-nitroso-α-D-glucopyranosyl chloride with alcohols was employed to synthesize the three α-D-glucopyranosyl deoxystreptamines and 4,6-di-O-α-D-glucopyranosyl deoxystreptamine. Effects of pH change on the n.m.r. spectra of kanamycins A and B and of the above synthetic compounds are interpreted in terms of a conformational change.

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Factors affecting movement of F-actin filaments propelled by skeletal muscle heavy meromyosin

AJP Cell Physiology ◽

10.1152/ajpcell.1992.262.3.c714 ◽

1992 ◽

Vol 262 (3) ◽

pp. C714-C723 ◽

Cited By ~ 163

Author(s):

E. Homsher ◽

F. Wang ◽

J. R. Sellers

Keyword(s):

Skeletal Muscle ◽

Ionic Strength ◽

Actin Filament ◽

Molecular Motors ◽

Actin Filaments ◽

Heavy Meromyosin ◽

Shortening Velocity ◽

Weakly Bound ◽

Factors Affecting ◽

Cross Bridges

The measurement of fluorescent-labeled actin filament movement driven by mechanoenzymes (e.g., myosin) is an important methodology for the study of molecular motors. It is assumed that the filament velocity (Vf) is analogous to the unloaded shortening velocity (Vu) seen in muscle fibers. Methods are described to reproducibly quantitate the movement of these filaments and to select uniformly moving filaments and specify their Vf. Use of these techniques allowed comparison of Vf to literature values for Vu with regard to [ATP], [ADP], [Pi], pH, ionic strength (10-150 mM), and temperature (15-30 degrees C). Vf and Vu are quantitatively similar with respect to the effects of substrate and product concentrations and temperatures greater than 20 degrees C. However, Vf is more sensitive to decreases in pH and temperatures less than 20 degrees C than Vu. At ionic strengths of 50-150 mM, Vf and Vu exhibit similar ionic strength dependencies (decreasing with ionic strength). At ionic strengths less than 50 mM, Vf is markedly reduced. Results of experiments using adenosine 5'-O-(3-thiotriphosphate) suggest that increasing the number of weakly bound cross bridges does not seriously affect Vf. Thus, although Vf is a good analogue for Vu under certain conditions (elevated ionic strength and temperatures greater than 20 degrees C), under others it is not. The results of motility assays must be cautiously interpreted.

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L-plastin Peptide Activation of αvβ3-mediated Adhesion Requires Integrin Conformational Change and Actin Filament Disassembly

Journal of Biological Chemistry ◽

10.1074/jbc.m007324200 ◽

2001 ◽

Vol 276 (17) ◽

pp. 14474-14481 ◽

Cited By ~ 30

Author(s):

Jun Wang ◽

Hua Chen ◽

Eric J. Brown

Keyword(s):

Conformational Change ◽

Actin Filament

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Allostery and molecular stripping mechanism in profilin regulated actin filament growth

New Journal of Physics ◽

10.1088/1367-2630/ac3b2d ◽

2021 ◽

Author(s):

Weiwei Zhang ◽

Yi Cao ◽

Wenfei Li ◽

Wei Wang

Keyword(s):

Conformational Change ◽

Actin Filament ◽

Crucial Role ◽

Ternary Complex ◽

Energy Landscape ◽

Growth Dynamics ◽

Landscape Model ◽

Allosteric Coupling ◽

Twist Conformation ◽

Pointed End

Abstract Profilin is an actin-sequestering protein and plays key role in regulating the polarized growth of actin filament. Binding of profilin to monomeric actin (G-actin) allows continuous elongation at the barbed end, but not the pointed end, of filament. How G-actin exchanges between the profilin-sequestered state and the filament state (F-actin) to support the barbed end elongation is not well understood. Here, we investigate the involved molecular mechanism by constructing a multi-basin energy landscape model and performing molecular simulations. We showed that the actin exchanging occurs by forming a ternary complex. The interactions arising from the barbed end binding drive the conformational change of the attached G-actin in the ternary complex from twist conformation to more flatten conformation without involving the change of nucleotide state, which in turn destabilizes the actin-profilin interface and promotes the profilin stripping event through allosteric coupling. We also showed that attachment of free profilin to the barbed end induces conformational change of the barbed end actin and facilitates its stripping from the filament. These results suggest a molecular stripping mechanism of the polarized actin filament growth dynamics controlled by the concentrations of the actin-profilin dimer and the free profilin, in which the allosteric feature of the monomeric actin plays crucial role.

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