7-helix_coiledcoil_LiuePNAS2007

7-helix_coiledcoil_LiuePNAS2007 - A seven-helix coiled coil...

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A seven-helix coiled coil Jie Liu, Qi Zheng, Yiqun Deng, Chao-Sheng Cheng, Neville R. Kallenbach, and Min Lu doi:10.1073/pnas.0604871103 2006;103;15457-15462; originally published online Oct 9, 2006; PNAS This information is current as of May 2007. Online Information www.pnas.org/cgi/content/full/103/42/15457 etc., can be found at: High-resolution figures, a citation map, links to PubMed and Google Scholar, References www.pnas.org/cgi/content/full/103/42/15457#BIBL This article cites 52 articles, 14 of which you can access for free at: www.pnas.org/cgi/content/full/103/42/15457#otherarticles This article has been cited by other articles: E-mail Alerts . click here at the top right corner of the article or Receive free email alerts when new articles cite this article - sign up in the box www.pnas.org/misc/rightperm.shtml To reproduce this article in part (figures, tables) or in entirety, see: Reprints www.pnas.org/misc/reprints.shtml To order reprints, see: Notes:
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A seven-helix coiled coil Jie Liu*, Qi Zheng*, Yiqun Deng*, Chao-Sheng Cheng*, Neville R. Kallenbach , and Min Lu* *Department of Biochemistry, Weill Medical College of Cornell University, New York, NY 10021; and Department of Chemistry, New York University, New York, NY 10003 Edited by Janet M. Thornton, European Bioinformatics Institute, Cambridge, United Kingdom, and approved August 28, 2006 (received for review June 12, 2006) Coiled-coil proteins contain a characteristic seven-residue se- quence repeat whose positions are designated a to g. The inter- acting surface between ± -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 -helical heptamer in aqueous solution. The 1.25-Å 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 -helices. protein design
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7-helix_coiledcoil_LiuePNAS2007 - A seven-helix coiled coil...

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