In a classical hypothesis of muscle contraction, the cyclic reorientations of myosin cross-bridges are the cause of contraction. However, this idea has recently been contested by the Electron Paramagnetic Resonance results which suggest that there exists only a single orientation of myosin. It is therefore essential to test, by alternative techniques, for the presence of different orientations of myosin. To this end, it is proposed to a) develop a method of measuring the spatial attitude of the isolated actomyosin in a gel, and b) test for the presence of the rotational motions of the cross-bridges by perturbation techniques. All experiments require a laser source and a microscope to determine cross-bridge orientation by measuring polarization of fluorescence of myosin-bound dye. In project 1, a new technique of measuring the orientation of isolated proteins oriented by gel electrophoresis is described, and it is proposed to apply this technique to measure the attitude of isolated myosin subfragment- 1 (S-1) with respect of F-actin during different steps in a sequence of intermediate states of actin-activated cycle of ATPase activity of S-1. In project 2, it is proposed to rapidly perturb a steady state population of active cross-bridges by depopulating a narrow angular sector of cross-bridges by a powerful polarized light pulse; the repopulation of this sector will provide the information about the rate of anticipated cross-bridge reorientations and will be followed by polarization methods. In project 3, it is proposed to use the wavelength-dependent polarization of fluorescence method in order to establish whether the angular reorientations induced by the addition of MgADP are a universal property of the cross-bridges, or whether they are observable only for specific probes. In project 4, it is proposed to use laser photolysis method to rapidly produce millimolar concentration of ATP by photolysis of photolysis """"""""caged"""""""" precursor of ATP previously diffused into muscle. This is expected to activate all cross-bridges simultaneously, and their rotational motion, if present, will be determined by polarization of fluorescence method. The health relatedness of these projects are that the information about the mechanism muscle contraction will ultimately lead to the positive intervention in diseases of muscle.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR040095-03
Application #
3160404
Study Section
Biophysical Chemistry Study Section (BBCB)
Project Start
1989-07-01
Project End
1994-05-31
Budget Start
1991-06-01
Budget End
1992-05-31
Support Year
3
Fiscal Year
1991
Total Cost
Indirect Cost
Name
Baylor Research Institute
Department
Type
Other Domestic Higher Education
DUNS #
096997515
City
Dallas
State
TX
Country
United States
Zip Code
75204
Midde, K; Dumka, V; Pinto, J R et al. (2011) Myosin cross-bridges do not form precise rigor bonds in hypertrophic heart muscle carrying troponin T mutations. J Mol Cell Cardiol 51:409-18
Mettikolla, P; Calander, N; Luchowski, R et al. (2011) Cross-bridge kinetics in myofibrils containing familial hypertrophic cardiomyopathy R58Q mutation in the regulatory light chain of myosin. J Theor Biol 284:71-81
Borejdo, J; Ushakov, D S; Moreland, R et al. (2001) The power stroke causes changes in the orientation and mobility of the termini of essential light chain 1 of myosin. Biochemistry 40:3796-803
Reshetnyak, Y K; Andreev, O A; Borejdo, J et al. (2000) The identification of tryptophan residues responsible for ATP-induced increase in intrinsic fluorescence of myosin subfragment 1. J Biomol Struct Dyn 18:113-25
Andreev, O A; Borejdo, J (1999) Binding of myosin cross-bridges to thin filaments of rabbit skeletal muscle. Biochem Biophys Res Commun 258:628-31
Andreev, O A; Borejdo, J (1997) Interaction of the heavy and light chains of cardiac myosin subfragment-1 with F-actin. Circ Res 81:688-93
Borejdo, J; Burlacu, S (1994) Orientation of actin filaments during motion in in vitro motility assay. Biophys J 66:1319-27
Andreeva, A L; Andreev, O A; Borejdo, J (1993) Structure of the 265-kilodalton complex formed upon EDC cross-linking of subfragment 1 to F-actin. Biochemistry 32:13956-60
Andreev, O A; Andreeva, A L; Markin, V S et al. (1993) Two different rigor complexes of myosin subfragment 1 and actin. Biochemistry 32:12046-53
Andreev, O A; Andreeva, A L; Borejdo, J (1993) Polarization of fluorescently labeled myosin subfragment-1 fully or partially decorating muscle fibers and myofibrils. Biophys J 65:1027-38

Showing the most recent 10 out of 18 publications