2hy6
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(New page: 200px<br /><applet load="2hy6" size="350" color="white" frame="true" align="right" spinBox="true" caption="2hy6, resolution 1.25Å" /> '''A seven-helix coiled...)
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Revision as of 18:31, 29 January 2008
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A seven-helix coiled coil
Overview
Coiled-coil proteins contain a characteristic seven-residue sequence, repeat whose positions are designated a to g. The interacting surface, between alpha-helices in a classical coiled coil is formed by, interspersing nonpolar side chains at the a and d positions with, hydrophilic residues at the flanking e and g positions. To explore how the, chemical nature of these core amino acids dictates the overall coiled-coil, architecture, we replaced all eight e and g residues in the GCN4 leucine, zipper with nonpolar alanine side chains. Surprisingly, the, alanine-containing mutant forms a stable alpha-helical heptamer in aqueous, solution. The 1.25-A resolution crystal structure of the heptamer reveals, a parallel seven-stranded coiled coil enclosing a large tubular channel, with an unusual heptad register shift between adjacent staggered helices., The overall geometry comprises two interleaved hydrophobic helical screws, of interacting cross-sectional a and d layers that have not been seen, before. Moreover, asparagines at the a positions play an essential role in, heptamer formation by participating in a set of buried interhelix hydrogen, bonds. These results demonstrate that heptad repeats containing four, hydrophobic positions can direct assembly of complex, higher-order, coiled-coil structures with rich diversity for close packing of, alpha-helices.
About this Structure
2HY6 is a Single protein structure of sequence from Saccharomyces cerevisiae with as ligand. Full crystallographic information is available from OCA.
Reference
A seven-helix coiled coil., Liu J, Zheng Q, Deng Y, Cheng CS, Kallenbach NR, Lu M, Proc Natl Acad Sci U S A. 2006 Oct 17;103(42):15457-62. Epub 2006 Oct 9. PMID:17030805
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