1ce9

HELIX CAPPING IN THE GCN4 LEUCINE ZIPPER

spinqualitylabelsall models 1ce9, resolution 1.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1ce9 is a 4 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum Function [GCN4_YEAST] Is a transcription factor that is responsible for the activation of more than 30 genes required for amino acid or for purine biosynthesis in response to amino acid or purine starvation. Binds and recognize the DNA sequence: 5'-TGA[CG]TCA-3'. Publication Abstract from PubMed Capping interactions associated with specific sequences at or near the ends of alpha-helices are important determinants of the stability of protein secondary and tertiary structure. We investigate here the role of the helix-capping motif Ser-X-X-Glu, a sequence that occurs frequently at the N termini of alpha helices in proteins, on the conformation and stability of the GCN4 leucine zipper. The 1.8 A resolution crystal structure of the capped molecule reveals distinct conformations, packing geometries and hydrogen-bonding networks at the amino terminus of the two helices in the leucine zipper dimer. The free energy of helix stabilization associated with the hydrogen-bonding and hydrophobic interactions in this capping structure is -1.2 kcal/mol, evaluated from thermal unfolding experiments. A single cap thus contributes appreciably to stabilizing the terminated helix and thereby the native state. These results suggest that helix capping plays a further role in protein folding, providing a sensitive connector linking alpha-helix formation to the developing tertiary structure of a protein. Helix capping in the GCN4 leucine zipper.,Lu M, Shu W, Ji H, Spek E, Wang L, Kallenbach NR J Mol Biol. 1999 May 14;288(4):743-52. PMID:10329176 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Gcn4

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