Among the myosin superfamily of motor proteins, myosin II is the sole filament forming isoform. Myosin IIs are hexamers containing two identical heavy chains and two pairs of light chains, the essential light chain and the regulatory light chain (RLC). Phosphorylation of the RLC by myosin light chain kinase is a general phenomenon in myosin IIs but the effect is variable depending on the source. The actin activated ATPase of both smooth and non-muscle myosin is regulated primarily by RLC phosphorylation. Vertebrate striated muscle myosins (cardiac and skeletal) also undergo RLC phosphorylation but the effect is only to modulate the ATPase activity which is regulated primarily by the troponin-tropomyosin complex on the thin filament. ATPase activity in many invertebrate striated muscle myosins is also controlled via myosin, not through light chain phosphorylation, but by Ca2+ binding to myosin at the interface between ELC and RLC. A common feature of myosin II regulation is the cooperative interaction between both myosin heads; myosin fragments that contain only one head are not regulated and are always """"""""on"""""""" with respect to their actin activated ATPase activity. We have recently obtained 2-D arrays of smooth muscle HMM, a two-headed, regulated fragment of myosin II, in both the dephosphorylated """"""""off"""""""" and phosphorylated """"""""on"""""""" states. These arrays are suitable for 3-imaging by electron crystallography and allow us to visualize for the first time, the head to head interactions that give rise to ATPase inhibition. The 2-D crystallization of HMM from myosin II facilitates study of regulation in a way not previously accessible. This application proposes to extend our observations on smooth muscle myosin regulation to other isoforms of myosin II, such as scallop striated, non-muscle and vertebrate striated muscle myosins in order to determine the generality of the structural interactions.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR047421-05
Application #
6846012
Study Section
Special Emphasis Panel (ZRG1-SSS-B (01))
Program Officer
Nuckolls, Glen H
Project Start
2001-02-15
Project End
2007-01-31
Budget Start
2005-02-01
Budget End
2007-01-31
Support Year
5
Fiscal Year
2005
Total Cost
$208,050
Indirect Cost
Name
Florida State University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
790877419
City
Tallahassee
State
FL
Country
United States
Zip Code
32306
Márquez, G; Pinto, A; Alamo, L et al. (2014) A method for 3D-reconstruction of a muscle thick filament using the tilt series images of a single filament electron tomogram. J Struct Biol 186:265-72
Taylor, Kenneth A; Feig, Michael; Brooks 3rd, Charles L et al. (2014) Role of the essential light chain in the activation of smooth muscle myosin by regulatory light chain phosphorylation. J Struct Biol 185:375-82
Winkler, Hanspeter; Wu, Shenping; Taylor, Kenneth A (2013) Electron tomography of paracrystalline 2D arrays. Methods Mol Biol 955:427-60
Baumann, Bruce A J; Taylor, Dianne W; Huang, Zhong et al. (2012) Phosphorylated smooth muscle heavy meromyosin shows an open conformation linked to activation. J Mol Biol 415:274-87
Winkler, Hanspeter; Zhu, Ping; Liu, Jun et al. (2009) Tomographic subvolume alignment and subvolume classification applied to myosin V and SIV envelope spikes. J Struct Biol 165:64-77
Taylor, Dianne W; Kelly, Deborah F; Cheng, Anchi et al. (2007) On the freezing and identification of lipid monolayer 2-D arrays for cryoelectron microscopy. J Struct Biol 160:305-12
Taylor, Kenneth A (2007) Regulation and recycling of myosin V. Curr Opin Cell Biol 19:67-74
Schoffstall, Brenda; Brunet, Nicolas M; Williams, Shanedah et al. (2006) Ca2+ sensitivity of regulated cardiac thin filament sliding does not depend on myosin isoform. J Physiol 577:935-44
Tama, Florence; Feig, Michael; Liu, Jun et al. (2005) The requirement for mechanical coupling between head and S2 domains in smooth muscle myosin ATPase regulation and its implications for dimeric motor function. J Mol Biol 345:837-54
Liu, Jun; Reedy, Mary C; Goldman, Yale E et al. (2004) Electron tomography of fast frozen, stretched rigor fibers reveals elastic distortions in the myosin crossbridges. J Struct Biol 147:268-82

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