8EFE

Human beta-cardiac myosin II bound to ADP-MG2+ and the associated essential light chain

Summary for 8EFE

• Entry DOI: 10.2210/pdb8efe/pdb
• EMDB information: 28081
• Descriptor: Beta-cardiac myosin II, Myosin light chain 1/3, skeletal muscle isoform, MAGNESIUM ION, ... (4 entities in total)
• Functional Keywords: actin, tropomyosin, myosin, cardiac, contractile protein
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 2
• Total formula weight: 120229.69

Authors

Doran, M.H.,Lehman, W.,Rynkiewicz, M.J. (deposition date: 2022-09-08, release date: 2023-01-11, Last modification date: 2024-06-19)

Primary citation

Doran, M.H.,Rynkiewicz, M.J.,Rassici, D.,Bodt, S.M.L.,Barry, M.E.,Bullitt, E.,Yengo, C.M.,Moore, J.R.,Lehman, W.
Conformational changes linked to ADP release from human cardiac myosin bound to actin-tropomyosin.
J.Gen.Physiol., 155:-, 2023

PubMed Abstract: Following binding to the thin filament, β-cardiac myosin couples ATP-hydrolysis to conformational rearrangements in the myosin motor that drive myofilament sliding and cardiac ventricular contraction. However, key features of the cardiac-specific actin-myosin interaction remain uncertain, including the structural effect of ADP release from myosin, which is rate-limiting during force generation. In fact, ADP release slows under experimental load or in the intact heart due to the afterload, thereby adjusting cardiac muscle power output to meet physiological demands. To further elucidate the structural basis of this fundamental process, we used a combination of cryo-EM reconstruction methodologies to determine structures of the human cardiac actin-myosin-tropomyosin filament complex at better than 3.4 Å-resolution in the presence and in the absence of Mg2+·ADP. Focused refinements of the myosin motor head and its essential light chains in these reconstructions reveal that small changes in the nucleotide-binding site are coupled to significant rigid body movements of the myosin converter domain and a 16-degree lever arm swing. Our structures provide a mechanistic framework to understand the effect of ADP binding and release on human cardiac β-myosin, and offer insights into the force-sensing mechanism displayed by the cardiac myosin motor.

PubMed: 36633586
DOI: 10.1085/jgp.202213267

Experimental method

ELECTRON MICROSCOPY (3.8 Å)