2b1f
Antiparallel four-stranded coiled coil specified by a 3-3-1 hydrophobic heptad repeatAntiparallel four-stranded coiled coil specified by a 3-3-1 hydrophobic heptad repeat
Structural highlights
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 PubMedCoiled-coil sequences in proteins commonly share a seven-amino acid repeat with nonpolar side chains at the first (a) and fourth (d) positions. We investigate here the role of a 3-3-1 hydrophobic repeat containing nonpolar amino acids at the a, d, and g positions in determining the structures of coiled coils using mutants of the GCN4 leucine zipper dimerization domain. When three charged residues at the g positions in the parental sequence are replaced by nonpolar alanine or valine side chains, stable four-helix structures result. The X-ray crystal structures of the tetramers reveal antiparallel, four-stranded coiled coils in which the a, d, and g side chains interlock in a combination of knobs-into-knobs and knobs-into-holes packing. Interfacial interactions in a coiled coil can therefore be prescribed by hydrophobic-polar patterns beyond the canonical 3-4 heptad repeat. The results suggest that the conserved, charged residues at the g positions in the GCN4 leucine zipper can impart a negative design element to disfavor thermodynamically more stable, antiparallel tetramers. Antiparallel four-stranded coiled coil specified by a 3-3-1 hydrophobic heptad repeat.,Deng Y, Liu J, Zheng Q, Eliezer D, Kallenbach NR, Lu M Structure. 2006 Feb;14(2):247-55. PMID:16472744[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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