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- Title
Structure and Biophysical Properties of a Triple-Stranded Beta-Helix Comprising the Central Spike of Bacteriophage T4.
- Authors
Buth, Sergey A.; Menin, Laure; Shneider, Mikhail M.; Engel, Jürgen; Boudko, Sergei P.; Leiman, Petr G.
- 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 complete β-helix.
- Subjects
BACTERIOPHAGE T4; PROTEIN folding; CRYSTALLOGRAPHY; FATTY acids; PROTEIN stability; AMINO acid sequence
- Publication
Viruses (1999-4915), 2015, Vol 7, Issue 8, p4676
- ISSN
1999-4915
- Publication type
Article
- DOI
10.3390/v7082839