The Structure of Gene Product 6 of Bacteriophage T4, the Hinge-Pin of the Baseplate

• DOI: 10.1016/j.str.2009.04.005
• Publication Date: 2009-06-10T12:22:35Z
• Authors: Anastasia A. Aksyuk; Petr G. Leiman; Mikhail M. Shneider; Vadim V. Mesyanzh...; Michael G. Rossmann
• Keywords: Models, Molecular; 0301 basic medicine; Genes, Viral; Protein Conformation; Cryoelectron Microscopy; Molecular Sequence Data; Protein Structure, Secondary; Protein Structure, Tertiary; 3. Good health; Viral Proteins; 03 medical and health sciences; Structural Biology; Bacteriophage T4; Amino Acid Sequence; Crystallization; Molecular Biology; Dimerization; Glycoproteins

The baseplate of bacteriophage T4 is a multicomponent protein complex, which controls phage attachment to the host. It assembles from six wedges and a central hub. During infection the baseplate undergoes a large conformational change from a dome-shaped to a flat, star-shaped structure. We report the crystal structure of the C-terminal half of gene product (gp) 6 and investigate its motion with respect to the other proteins during the baseplate rearrangement. Six gp6 dimers interdigitate, forming a ring that maintains the integrity of the baseplate in both conformations. One baseplate wedge contains an N-terminal dimer of gp6, whereas neighboring wedges are tied together through the C-terminal dimer of gp6. The dimeric interactions are preserved throughout the rearrangement of the baseplate. However, the hinge angle between the N- and C-terminal parts of gp6 changes by approximately 15 degrees , accounting for a 10 A radial increase in the diameter of the gp6 ring.