title: Structure and Biophysical Properties of a Triple-Stranded Beta-Helix Comprising the Central Spike of Bacteriophage T4.
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.
authors: Institute of Physics of Biological Systems, École Polytechnique Fédérale de Lausanne (EPFL), BSP 415, 1015 Lausanne, Switzerland. sergii.buth@epfl.ch.
authors: Sergey A
authors: SA
authors: Buth
authors: Service de Spectrométrie de Masse, ISIC, EPFL, BCH 1520, 1015 Lausanne, Switzerland. laure.menin@epfl.ch.
authors: Laure
authors: L
authors: Menin
authors: Institute of Physics of Biological Systems, École Polytechnique Fédérale de Lausanne (EPFL), BSP 415, 1015 Lausanne, Switzerland. mm_shn@mail.ru.|Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Laboratory of Molecular Bioengineering, 16/10 Miklukho-Maklaya St., 117997 Moscow, Russia. mm_shn@mail.ru.
authors: Mikhail M
authors: MM
authors: Shneider
authors: Department of Biophysical Chemistry, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland. juergen.engel@unibas.ch.
authors: Jürgen
authors: J
authors: Engel
authors: Department of Biophysical Chemistry, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland. spb@shcc.org.|Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907-2054, USA. spb@shcc.org.|The Research Department, Shriner's Hospital for Children, 3101 Sam Jackson Park Road, Portland, OR 97239, USA. spb@shcc.org.|Department of Biochemistry and Molecular Biology, Oregon Health and Science University, 3181 Sam Jackson Park Road, Portland, OR 97239, USA. spb@shcc.org.
authors: Sergei P
authors: SP
authors: Boudko
authors: Institute of Physics of Biological Systems, École Polytechnique Fédérale de Lausanne (EPFL), BSP 415, 1015 Lausanne, Switzerland. petr.leiman@epfl.ch.|Department of Biological Sciences, Purdue University, 915 W. State Street, West Lafayette, IN 47907-2054, USA. petr.leiman@epfl.ch.
authors: Petr G
authors: PG
authors: Leiman
mesh_terms: D017122:Bacteriophage T4 / Q000737:chemistry* / Q000378:metabolism; D055592:Biophysical Phenomena; D018360:Crystallography, X-Ray; D005227:Fatty Acids / Q000032:analysis; D013058:Mass Spectrometry; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D014764:Viral Proteins / Q000737:chemistry*
chemical_list: D005227:Fatty Acids; D014764:Viral Proteins; C068293:gene 5 protein, Enterobacteria phage T4
keywords: X-ray crystallography; amyloid-like structure; fatty acid; fibrous proteins; intrinsic protein fluorescence; low complexity amino acid sequence; mass spectrometry; protein folding; protein stability; β-helical proteins