Atomic structure of a tryptophan-zipper pentamer

Jie Liu, Wei Yong, Yiqun Deng, Neville R. Kallenbach, Min Lu

Research output: Contribution to journalArticlepeer-review

Abstract

Coiled-coil motifs are ubiquitous mediators of specific protein-protein interactions through the formation of interlocking hydrophobic seams between α-helical chains. Residues that form these seams occur at the first (a) and fourth (d) positions of a characteristic 7-aa repeat and are primarily aliphatic. The potential of aromatic residues to promote helix association in a coiled coil was explored by engineering a "Trp-zipper" protein with Trp residues at all 14 a and d positions. The protein forms a discrete, stable, α-helical pentamer in water at physiological pH. Its 1.45-Å crystal structure reveals a parallel, five-stranded coiled coil, a previously uncharacterized type of "knobs-into-holes" packing interaction between interfacial Trp side chains, and an unusual ≈8-Å-diameter axial channel lined with indole rings that is filled with polyethylene glycol 400 and water and sulfate ion molecules. The engineered Trp-zipper pentamer enlarges current views of coiled-coil assembly, molecular recognition, and protein engineering, and may serve as a soluble model for membrane ion channels.

Original languageEnglish (US)
Pages (from-to)16156-16161
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume101
Issue number46
DOIs
StatePublished - Nov 16 2004

Keywords

  • Coiled coils
  • Protein design
  • Protein structure

ASJC Scopus subject areas

  • General

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