2ipz

A Parallel Coiled-Coil Tetramer with Offset Helices

spinqualitylabelsall models 2ipz, resolution 1.35Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2ipz is a 4 chain structure with sequence from Saccharomyces cerevisiae. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.35Å Ligands: GOL, IPA Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT 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 Specific helix-helix interactions are fundamental in assembling the native state of proteins and in protein-protein interfaces. Coiled coils afford a unique model system for elucidating principles of molecular recognition between alpha helices. The coiled-coil fold is specified by a characteristic seven amino acid repeat containing hydrophobic residues at the first (a) and fourth (d) positions. Nonpolar side chains spaced three and four residues apart are referred to as the 3-4 hydrophobic repeat. The presence of apolar amino acids at the e or g positions (corresponding to a 3-3-1 hydrophobic repeat) can provide new possibilities for close-packing of alpha-helices that includes examples such as the lac repressor tetramerization domain. Here we demonstrate that an unprecedented coiled-coil interface results from replacement of three charged residues at the e positions in the dimeric GCN4 leucine zipper by nonpolar valine side chains. Equilibrium circular dichroism and analytical ultracentrifugation studies indicate that the valine-containing mutant forms a discrete alpha-helical tetramer with a significantly higher stability than the parent leucine-zipper molecule. The 1.35 A resolution crystal structure of the tetramer reveals a parallel four-stranded coiled coil with a three-residue interhelical offset. The local packing geometry of the three hydrophobic positions in the tetramer conformation is completely different from that seen in classical tetrameric structures yet bears resemblance to that in three-stranded coiled coils. These studies demonstrate that distinct van der Waals interactions beyond the a and d side chains can generate a diverse set of helix-helix interfaces and three-dimensional supercoil structures. A parallel coiled-coil tetramer with offset helices.,Liu J, Deng Y, Zheng Q, Cheng CS, Kallenbach NR, Lu M Biochemistry. 2006 Dec 26;45(51):15224-31. Epub 2006 Nov 29. PMID:17176044 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Gcn4 3D Structures Gnc4 3D Structures

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