title: Structure of the Receptor-Binding Carboxy-Terminal Domain of the Bacteriophage T5 L-Shaped Tail Fibre with and without Its Intra-Molecular Chaperone.
abstract: Bacteriophage T5, a Siphovirus belonging to the order Caudovirales, has a flexible, three-fold symmetric tail, to which three L-shaped fibres are attached. These fibres recognize oligo-mannose units on the bacterial cell surface prior to infection and are composed of homotrimers of the pb1 protein. Pb1 has 1396 amino acids, of which the carboxy-terminal 133 residues form a trimeric intra-molecular chaperone that is auto-proteolyzed after correct folding. The structure of a trimer of residues 970-1263 was determined by single anomalous dispersion phasing using incorporated selenomethionine residues and refined at 2.3 Å resolution using crystals grown from native, methionine-containing, protein. The protein inhibits phage infection by competition. The phage-distal receptor-binding domain resembles a bullet, with the walls formed by partially intertwined beta-sheets, conferring stability to the structure. The fold of the domain is novel and the topology unique to the pb1 structure. A site-directed mutant (Ser1264 to Ala), in which auto-proteolysis is impeded, was also produced, crystallized and its 2.5 Å structure solved by molecular replacement. The additional chaperone domain (residues 1263-1396) consists of a central trimeric alpha-helical coiled-coil flanked by a mixed alpha-beta domain. Three long beta-hairpin tentacles, one from each chaperone monomer, extend into long curved grooves of the bullet-shaped domain. The chaperone-containing mutant did not inhibit infection by competition.
authors.affiliation: Departamento de Estructura de Macromoléculas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), calle Darwin 3, E-28049 Madrid, Spain. c.garcia@bioc.uzh.ch.
authors.forename: Carmela
authors.initials: C
authors.lastname: Garcia-Doval
authors.affiliation: Departamento de Estructura de Macromoléculas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), calle Darwin 3, E-28049 Madrid, Spain. jrcaston@cnb.csic.es.
authors.forename: José R
authors.initials: JR
authors.lastname: Castón
authors.affiliation: Departamento de Estructura de Macromoléculas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), calle Darwin 3, E-28049 Madrid, Spain. dluque@cnb.csic.es.|Centro Nacional de Microbiología, ISCIII, Majadahonda, E-28220 Madrid, Spain. dluque@cnb.csic.es.
authors.forename: Daniel
authors.initials: D
authors.lastname: Luque
authors.affiliation: Departamento de Estructura de Macromoléculas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), calle Darwin 3, E-28049 Madrid, Spain. meritxell.granell@cbs.cnrs.fr.
authors.forename: Meritxell
authors.initials: M
authors.lastname: Granell
authors.affiliation: Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Spain. jose.otero@usc.es.
authors.forename: José M
authors.initials: JM
authors.lastname: Otero
authors.affiliation: Unidade de Raios X, RIAIDT, Universidade de Santiago de Compostela, E-15782 Santiago de Compostela, Spain. antonio.llamas@usc.es.
authors.forename: Antonio L
authors.initials: AL
authors.lastname: Llamas-Saiz
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, F-91198 Gif-sur-Yvette cedex, France. madalena.renouard@i2bc.paris-saclay.fr.
authors.forename: Madalena
authors.initials: M
authors.lastname: Renouard
authors.affiliation: Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, F-91198 Gif-sur-Yvette cedex, France. pascale.boulanger@i2bc.paris-saclay.fr.
authors.forename: Pascale
authors.initials: P
authors.lastname: Boulanger
authors.affiliation: Departamento de Estructura de Macromoléculas, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), calle Darwin 3, E-28049 Madrid, Spain. mjvanraaij@cnb.csic.es.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: van Raaij
mesh_terms: D017899:Caudovirales / Q000737:chemistry / Q000502:physiology; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics; D011487:Protein Conformation; D017906:Siphoviridae / Q000737:chemistry* / Q000502:physiology; D017376:Viral Tail Proteins / Q000737:chemistry* / Q000235:genetics; D053585:Virus Attachment
chemical_list: D018832:Molecular Chaperones; D050505:Mutant Proteins; D017376:Viral Tail Proteins
keywords: Caudovirales; J0101; Siphoviridae; bacterial viruses; crystallography; infection