View source for 2ccn

[[Image:2ccn.gif|left|200px]]<br /><applet load="2ccn" size="450" color="white" frame="true" align="right" spinBox="true" 
caption="2ccn, resolution 1.60&Aring;" />
'''PLI E20C IS ANTIPARALLEL'''<br />

==Overview==
A detailed understanding of the mechanisms by which particular amino acid, sequences can give rise to more than one folded structure, such as for, proteins that undergo large conformational changes or misfolding, is a, long-standing objective of protein chemistry. Here, we describe the, crystal structures of a single coiled-coil peptide in distinct parallel, and antiparallel tetrameric configurations and further describe the, parallel or antiparallel crystal structures of several related peptide, sequences; the antiparallel tetrameric assemblies represent the first, crystal structures of GCN4-derived peptides exhibiting such a, configuration. Intriguingly, substitution of a single solvent-exposed, residue enabled the parallel coiled-coil tetramer GCN4-pLI to populate the, antiparallel configuration, suggesting that the two configurations are, close enough in energy for subtle sequence changes to have important, structural consequences. We present a structural analysis of the small, changes to the helix register and side-chain conformations that, accommodate the two configurations and have supplemented these results, using solution studies and a molecular dynamics energetic analysis using a, replica exchange methodology. Considering the previous examples of, structural nonspecificity in coiled-coil peptides, the findings reported, here not only emphasize the predisposition of the coiled-coil motif to, adopt multiple configurations but also call attention to the associated, risk that observed crytstal structures may not represent the only (or even, the major) species present in solution.

==About this Structure==
2CCN is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae]. This structure superseeds the now removed PDB entry 1VZL. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2CCN OCA]. 

==Reference==
Coiled coils at the edge of configurational heterogeneity. Structural analyses of parallel and antiparallel homotetrameric coiled coils reveal configurational sensitivity to a single solvent-exposed amino acid substitution., Yadav MK, Leman LJ, Price DJ, Brooks CL 3rd, Stout CD, Ghadiri MR, Biochemistry. 2006 Apr 11;45(14):4463-73. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=16584182 16584182]
[[Category: Saccharomyces cerevisiae]]
[[Category: Single protein]]
[[Category: Ghadiri, M.R.]]
[[Category: III, C.L.Brooks.]]
[[Category: Leman, L.J.]]
[[Category: Price, D.J.]]
[[Category: Stout, C.D.]]
[[Category: Yadav, M.K.]]
[[Category: activator]]
[[Category: amino-acid biosynthesis]]
[[Category: antiparallel]]
[[Category: dna-binding]]
[[Category: four helix bundle]]
[[Category: nuclear protein]]
[[Category: parallel]]
[[Category: pli]]
[[Category: transcription]]
[[Category: transcription regulation]]

''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 09:04:56 2007''