Conformational Transition between Four and Five-stranded Phenylalanine Zippers Determined by a Local Packing Interaction

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

Research output: Contribution to journalArticle

Abstract

Alpha-helical coiled coils play a crucial role in mediating specific protein-protein interactions. However, the rules and mechanisms that govern helix-helix association in coiled coils remain incompletely understood. Here we have engineered a seven heptad "Phe-zipper" protein (Phe-14) with phenylalanine residues at all 14 hydrophobic a and d positions, and generated a further variant (Phe-14M) in which a single core Phe residue is substituted with Met. Phe-14 forms a discrete α-helical pentamer in aqueous solution, while Phe-14M folds into a tetrameric helical structure. X-ray crystal structures reveal that in both the tetramer and the pentamer the a and d side-chains interlock in a classical knobs-into-holes packing to produce parallel coiled-coil structures enclosing large tubular cavities. However, the presence of the Met residue in the apolar interface of the tetramer markedly alters its local coiled-coil conformation and superhelical geometry. Thus, short-range interactions involving the Met side-chain serve to preferentially select for tetramer formation, either by inhibiting a nucleation step essential for pentamer folding or by abrogating an intermediate required to form the pentamer. Although specific trigger sequences have not been clearly identified in dimeric coiled coils, higher-order coiled coils, as well as other oligomeric multi-protein complexes, may require such sequences to nucleate and direct their assembly.

Original languageEnglish (US)
Pages (from-to)168-179
Number of pages12
JournalJournal of Molecular Biology
Volume361
Issue number1
DOIs
StatePublished - Aug 4 2006

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Phenylalanine
Proteins
X-Rays

Keywords

  • coiled coils
  • protein engineering
  • protein folding
  • protein structure

ASJC Scopus subject areas

  • Virology

Cite this

Conformational Transition between Four and Five-stranded Phenylalanine Zippers Determined by a Local Packing Interaction. / Liu, Jie; Zheng, Qi; Deng, Yiqun; Kallenbach, Neville R.; Lu, Min.

In: Journal of Molecular Biology, Vol. 361, No. 1, 04.08.2006, p. 168-179.

Research output: Contribution to journalArticle

Liu, Jie ; Zheng, Qi ; Deng, Yiqun ; Kallenbach, Neville R. ; Lu, Min. / Conformational Transition between Four and Five-stranded Phenylalanine Zippers Determined by a Local Packing Interaction. In: Journal of Molecular Biology. 2006 ; Vol. 361, No. 1. pp. 168-179.
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