2r2v

Sequence Determinants of the Topology of the Lac Repressor Tetrameric Coiled Coil

spinqualitylabelsall models 2r2v, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2r2v is a 8 chain structure with sequence from Saccharomyces cerevisiae. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ACT, CIT, ZN Related: 2zta Gene: GCN4, AAS3, ARG9 (SACCHAROMYCES CEREVISIAE) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed Predictive understanding of how the folded, functional shape of a native protein is encoded in the linear sequence of its amino acid residues remains an unsolved challenge in modern structural biology. Antiparallel four-stranded coiled coils are relatively simple protein structures that embody a heptad sequence repeat and rich diversity for tertiary packing of alpha-helices. To explore specific sequence determinants of the lac repressor coiled-coil tetramerization domain, we have engineered a set of buried nonpolar side chains at the a-, d-, and e-positions into the hydrophobic interior of the dimeric GCN4 leucine zipper. Circular dichroism and equilibrium ultracentrifugation studies show that this core variant (GCN4-pAeLV) forms a stable tetrameric structure with a reversible and highly cooperative thermal unfolding transition. The X-ray crystal structure at 1.9 A reveals that GCN4-pAeLV is an antiparallel four-stranded coiled coil of the lac repressor type in which the a, d, and e side chains associate by means of combined knobs-against-knobs and knobs-into-holes packing with a characteristic interhelical offset of 0.25 heptad. Comparison of the side chain shape and packing in the antiparallel tetramers shows that the burial of alanine residues at the e positions between the neighboring helices of GCN4-pAeLV dictates both the antiparallel orientation and helix offset. This study fills in a gap in our knowledge of the determinants of structural specificity in antiparallel coiled coils and improves our understanding of how specific side chain packing forms the teritiary structure of a functional protein. Conformational specificity of the lac repressor coiled-coil tetramerization domain.,Liu J, Zheng Q, Deng Y, Li Q, Kallenbach NR, Lu M Biochemistry. 2007 Dec 25;46(51):14951-9. Epub 2007 Dec 4. PMID:18052214 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Gnc4 3D Structures Lac repressor

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