1p9i

[[Image:1p9i.jpg|left|200px]]

|PDB= 1p9i |SIZE=350|CAPTION= <scene name='initialview01'>1p9i</scene>, resolution 1.17&Aring;

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|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1p9i FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1p9i OCA], [http://www.ebi.ac.uk/pdbsum/1p9i PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1p9i RCSB]</span>

 

 

 

We determined the 1.17 A resolution X-ray crystal structure of a hybrid peptide based on sequences from coiled-coil regions of the proteins GCN4 and cortexillin I. The peptide forms a parallel homodimeric coiled-coil, with C(alpha) backbone geometry similar to GCN4 (rmsd value 0.71 A). Three stabilizing interactions have been identified: a unique hydrogen bonding-electrostatic network not previously observed in coiled-coils, and two other hydrophobic interactions involving leucine residues at positions e and g from both g-a' and d-e' interchain interactions with the hydrophobic core. This is also the first report of the quantitative significance of these interactions. The GCN4/cortexillin hybrid surprisingly has two interchain Glu-Lys' ion pairs that form a hydrogen bonding network with the Asn residues in the core. This network, which was not observed for the reversed Lys-Glu' pair in GCN4, increases the combined stability contribution of each Glu-Lys' salt bridge across the central Asn15-Asn15' core to approximately 0.7 kcal/mole, compared to approximately 0.4 kcal mole(-1) from a Glu-Lys' salt bridge on its own. In addition to electrostatic and hydrogen bonding stabilization of the coiled-coil, individual leucine residues at positions e and g in the hybrid peptide also contribute to stability by 0.7 kcal/mole relative to alanine. These interactions are of critical importance to understanding the stability requirements for coiled-coil folding and in modulating the stability of de novo designed macromolecules containing this motif.

 

1P9I is a [[Protein complex]] structure of sequences from [http://en.wikipedia.org/wiki/ ]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1P9I OCA].

 

Unique stabilizing interactions identified in the two-stranded alpha-helical coiled-coil: crystal structure of a cortexillin I/GCN4 hybrid coiled-coil peptide., Lee DL, Ivaninskii S, Burkhard P, Hodges RS, Protein Sci. 2003 Jul;12(7):1395-405. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/12824486 12824486]

[[Category: Protein complex]]

[[Category: Ivaninskii, S.]]