2FXO image
Deposition Date 2006-02-06
Release Date 2006-11-21
Last Version Date 2024-10-23
Entry Detail
PDB ID:
2FXO
Title:
Structure of the human beta-myosin S2 fragment
Biological Source:
Source Organism:
Homo sapiens (Taxon ID: 9606)
Host Organism:
Method Details:
Experimental Method:
Resolution:
2.50 Å
R-Value Free:
0.34
R-Value Work:
0.27
R-Value Observed:
0.27
Space Group:
P 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Molecule:Myosin heavy chain, cardiac muscle beta isoform
Gene (Uniprot):MYH7
Mutations:E924K
Chain IDs:A, B, C, D
Chain Length:129
Number of Molecules:4
Biological Source:Homo sapiens
Ligand Molecules
Primary Citation
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)
PMID: 17095604 DOI: 10.1073/pnas.0606741103

Abstact

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.

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Primary Citation of related structures