2FXO

Structure of the human beta-myosin S2 fragment

Summary for 2FXO

• Entry DOI: 10.2210/pdb2fxo/pdb
• Related: 1nkn 2fxm
• Descriptor: Myosin heavy chain, cardiac muscle beta isoform (1 entity in total)
• Functional Keywords: coiled coil (dimeric, parallel), familial hypertrophic cardiomyopathy, fhc-associated mutant e924k, thick filament, contractile protein
• Biological source: Homo sapiens (human)
• Cellular location: Cytoplasm, myofibril : P12883
• Total number of polymer chains: 4
• Total formula weight: 60424.58

Authors

Blankenfeldt, W.,Thoma, N.H.,Wray, J.S.,Gautel, M.,Schlichting, I. (deposition date: 2006-02-06, release date: 2006-11-21, Last modification date: 2024-10-23)

Primary citation

Blankenfeldt, W.,Thoma, N.H.,Wray, J.S.,Gautel, M.,Schlichting, I.
Crystal structures of human cardiac {beta}-myosin II S2-{Delta} provide insight into the functional role of the S2 subfragment
Proc.Natl.Acad.Sci.Usa, 103:17713-17717, 2006

PubMed Abstract: Myosin II is the major component of the muscle thick filament. It consists of two N-terminal S1 subfragments ("heads") connected to a long dimeric coiled-coil rod. The rod is in itself twofold symmetric, but in the filament, the two heads point away from the filament surface and are therefore not equivalent. This breaking of symmetry requires the initial section of the rod, subfragment 2 (S2), to be relatively flexible. S2 is an important functional element, involved in various mechanisms by which the activity of smooth and striated muscle is regulated. We have determined crystal structures of the 126 N-terminal residues of S2 from human cardiac beta-myosin II (S2-Delta), of both WT and the disease-associated E924K mutant. S2-Delta is a straight parallel dimeric coiled coil, but the N terminus of one chain is disordered in WT-S2-Delta due to crystal contacts, indicative of unstable local structure. Bulky noncanonical side chains pack into a/d positions of S2-Delta's N terminus, leading to defined local asymmetry and axial stagger, which could induce nonequivalence of the S1 subfragments. Additionally, S2 possesses a conserved charge distribution with three prominent rings of negative potential within S2-Delta, the first of which may provide a binding interface for the "blocked head" of smooth muscle myosin in the OFF state. The observation that many disease-associated mutations affect the second negatively charged ring further suggests that charge interactions play an important role in regulation of cardiac muscle activity through myosin-binding protein C.

PubMed: 17095604
DOI: 10.1073/pnas.0606741103

Experimental method

X-RAY DIFFRACTION (2.5 Å)