1nkn
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(New page: 200px<br /><applet load="1nkn" size="450" color="white" frame="true" align="right" spinBox="true" caption="1nkn, resolution 2.50Å" /> '''VISUALIZING AN UNSTA...)
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Revision as of 20:13, 20 November 2007
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VISUALIZING AN UNSTABLE COILED COIL: THE CRYSTAL STRUCTURE OF AN N-TERMINAL SEGMENT OF THE SCALLOP MYOSIN ROD
Overview
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.
About this Structure
1NKN is a Protein complex structure of sequences from Argopecten irradians, saccharomyces cerevisiae. Full crystallographic information is available from OCA.
Reference
Visualization of an unstable coiled coil from the scallop myosin rod., Li Y, Brown JH, Reshetnikova L, Blazsek A, Farkas L, Nyitray L, Cohen C, Nature. 2003 Jul 17;424(6946):341-5. PMID:12867988
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