title: Structure of the T4 baseplate and its function in triggering sheath contraction.
abstract: Several systems, including contractile tail bacteriophages, the type VI secretion system and R-type pyocins, use a multiprotein tubular apparatus to attach to and penetrate host cell membranes. This macromolecular machine resembles a stretched, coiled spring (or sheath) wound around a rigid tube with a spike-shaped protein at its tip. A baseplate structure, which is arguably the most complex part of this assembly, relays the contraction signal to the sheath. Here we present the atomic structure of the approximately 6-megadalton bacteriophage T4 baseplate in its pre- and post-host attachment states and explain the events that lead to sheath contraction in atomic detail. We establish the identity and function of a minimal set of components that is conserved in all contractile injection systems and show that the triggering mechanism is universally conserved.
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), BSP-415, 1015 Lausanne, Switzerland.
authors.forename: Nicholas M I
authors.initials: NM
authors.lastname: Taylor
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), BSP-415, 1015 Lausanne, Switzerland.|Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences, pr. 60-letiya Oktyabrya, 7 build. 2, 117312, Moscow, Russia.
authors.forename: Nikolai S
authors.initials: NS
authors.lastname: Prokhorov
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), BSP-415, 1015 Lausanne, Switzerland.
authors.forename: Ricardo C
authors.initials: RC
authors.lastname: Guerrero-Ferreira
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), BSP-415, 1015 Lausanne, Switzerland.|Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Laboratory of Molecular Bioengineering, 16/10 Miklukho-Maklaya St., 117997 Moscow, Russia.
authors.forename: Mikhail M
authors.initials: MM
authors.lastname: Shneider
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), BSP-415, 1015 Lausanne, Switzerland.
authors.forename: Christopher
authors.initials: C
authors.lastname: Browning
authors.affiliation: Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Mattenstrasse 26, 4058 Basel, Switzerland.
authors.forename: Kenneth N
authors.initials: KN
authors.lastname: Goldie
authors.affiliation: Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Mattenstrasse 26, 4058 Basel, Switzerland.
authors.forename: Henning
authors.initials: H
authors.lastname: Stahlberg
authors.affiliation: École Polytechnique Fédérale de Lausanne (EPFL), BSP-415, 1015 Lausanne, Switzerland.
authors.forename: Petr G
authors.initials: PG
authors.lastname: Leiman
mesh_terms: D017122:Bacteriophage T4 / Q000737:chemistry* / Q000648:ultrastructure*; D020285:Cryoelectron Microscopy; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D011487:Protein Conformation; D015678:Viral Structural Proteins / Q000737:chemistry* / Q000648:ultrastructure*
chemical_list: D015678:Viral Structural Proteins