Antiparallel four-stranded coiled coil specified by a 3-3-1 hydrophobic heptad repeat

Yiqun Deng, Jie Liu, Qi Zheng, David Eliezer, Neville R. Kallenbach, Min Lu

Research output: Contribution to journalArticlepeer-review

Abstract

Coiled-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.

Original languageEnglish (US)
Pages (from-to)247-255
Number of pages9
JournalStructure
Volume14
Issue number2
DOIs
StatePublished - Feb 2006

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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