1NKN

VISUALIZING AN UNSTABLE COILED COIL: THE CRYSTAL STRUCTURE OF AN N-TERMINAL SEGMENT OF THE SCALLOP MYOSIN ROD

Summary for 1NKN

• Entry DOI: 10.2210/pdb1nkn/pdb
• Descriptor: S2N51-GCN4 (2 entities in total)
• Functional Keywords: alpha helix, coiled coil, contractile protein
• Biological source: Argopecten irradians, Saccharomyces cerevisiae (, baker's yeast)
• Cellular location: Nucleus: P03069
• Total number of polymer chains: 4
• Total formula weight: 42236.70

Authors

Li, Y.,Brown, J.H.,Reshetnikova, L.,Blazsek, A.,Farkas, L.,Nyitray, L.,Cohen, C. (deposition date: 2003-01-03, release date: 2003-07-22, Last modification date: 2024-02-14)

Primary citation

Li, Y.,Brown, J.H.,Reshetnikova, L.,Blazsek, A.,Farkas, L.,Nyitray, L.,Cohen, C.
Visualization of an unstable coiled coil from the scallop myosin rod
Nature, 424:341-345, 2003

PubMed Abstract: Alpha-helical coiled coils in muscle exemplify simplicity and economy of protein design: small variations in sequence lead to remarkable diversity in cellular functions. Myosin II is the key protein in muscle contraction, and the molecule's two-chain alpha-helical coiled-coil rod region--towards the carboxy terminus of the heavy chain--has unusual structural and dynamic features. The amino-terminal subfragment-2 (S2) domains of the rods can swing out from the thick filament backbone at a hinge in the coiled coil, allowing the two myosin 'heads' and their motor domains to interact with actin and generate tension. Most of the S2 rod appears to be a flexible coiled coil, but studies suggest that the structure at the N-terminal region is unstable, and unwinding or bending of the alpha-helices near the head-rod junction seems necessary for many of myosin's functional properties. Here we show the physical basis of a particularly weak coiled-coil segment by determining the 2.5-A-resolution crystal structure of a leucine-zipper-stabilized fragment of the scallop striated-muscle myosin rod adjacent to the head-rod junction. The N-terminal 14 residues are poorly ordered; the rest of the S2 segment forms a flexible coiled coil with poorly packed core residues. The unusual absence of interhelical salt bridges here exposes apolar core atoms to solvent.

PubMed: 12867988
DOI: 10.1038/nature01801

Experimental method

X-RAY DIFFRACTION (2.5 Å)