Structure and Biophysical Properties of a Triple-Stranded Beta-Helix Comprising the Central Spike of Bacteriophage T4

Viruses

Sergey A. Buth²  Laure Menin¹  Mikhail M. Shneider²  Jürgen Engel³  Sergei P. Boudko³  Petr G. Leiman²  Rob Lavigne⁴ 

[1] Service de Spectrométrie de Masse, ISIC, EPFL, BCH 1520, 1015 Lausanne, Switzerland; E-Mail:;Institute of Physics of Biological Systems, École Polytechnique Fédérale de Lausanne (EPFL), BSP 415, 1015 Lausanne, Switzerland; E-Mails:;Department of Biophysical Chemistry, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland; E-Mail:Institute of Physics of Biological Systems, École Polytechnique Fédérale de Lausanne (EPFL), BSP 415, 1015 Lausanne, Switzerland;

关键词: β-helical proteins;    fibrous proteins;    protein folding;    X-ray crystallography;    fatty acid;    mass spectrometry;    intrinsic protein fluorescence;    protein stability;    amyloid-like structure;    low complexity amino acid sequence;   

DOI  :  10.3390/v7082839

来源: mdpi

【 摘 要 】

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.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.