Structure and biophysical properties of a triple-stranded beta-helix comprising the central spike of bacteriophage T4

Sergey A. Buth, Laure Menin, Mikhail M. Shneider, Jürgen Engel, Sergei P. Boudko, Petr G. Leiman

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Gene product 5 (gp5) of bacteriophage T4 is a spike-shaped protein that functions to disrupt the membrane of the target cell during phage infection. Its C-terminal domain is a long and slender β-helix that is formed by three polypeptide chains wrapped around a common symmetry axis akin to three interdigitated corkscrews. The folding and biophysical properties of such triple-stranded β-helices, which are topologically related to amyloid fibers, represent an unsolved biophysical problem. Here, we report structural and biophysical characterization of T4 gp5 β-helix and its truncated mutants of different lengths. A soluble fragment that forms a dimer of trimers and that could comprise a minimal self-folding unit has been identified. Surprisingly, the hydrophobic core of the β-helix is small. It is located near the C-terminal end of the β-helix and contains a centrally positioned and hydrated magnesium ion. A large part of the β-helix interior comprises a large elongated cavity that binds palmitic, stearic, and oleic acids in an extended conformation suggesting that these molecules might participate in the folding of the completeβ-helix.

Original languageEnglish (US)
Pages (from-to)4676-4706
Number of pages31
JournalViruses
Volume7
Issue number8
DOIs
StatePublished - Aug 18 2015

Keywords

  • Amyloid-like structure
  • Fatty acid
  • Fibrous proteins
  • Intrinsic protein fluorescence
  • Low complexity amino acid sequence
  • Mass spectrometry
  • Protein folding
  • Protein stability
  • X-ray crystallography
  • β-Helical proteins

ASJC Scopus subject areas

  • Infectious Diseases
  • Virology

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