Structure of the Receptor-Binding Carboxy-Terminal Domain of the Bacteriophage T5 L-Shaped Tail Fibre with and without Its Intra-Molecular Chaperone

García Doval, CarmelaCastón, José R.Luque, DanielGranell, MeritxellOtero Casas, José ManuelLlamas Saiz, Antonio LuisRenouard, MadalenaBoulanger, PascaleRaaij, Mark J. van2020-12-012020-12-012015Garcia-Doval, C.; Castón, J.R.; Luque, D.; Granell, M.; Otero, J.M.; Llamas-Saiz, A.L.; Renouard, M.; Boulanger, P.; Van Raaij, M.J. Structure of the Receptor-Binding Carboxy-Terminal Domain of the Bacteriophage T5 L-Shaped Tail Fibre with and without Its Intra-Molecular Chaperone. Viruses 2015, 7, 6424-6440http://hdl.handle.net/10347/23883Bacteriophage 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 competitioneng© 2015 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons by Attribution (CC-BY) license (http://creativecommons.org/licenses/by/4.0/)Atribución 4.0 Internacionalhttp://creativecommons.org/licenses/by/4.0/Bacterial virusesCaudoviralesSiphoviridaeCrystallographyInfectionJ0101Structure of the Receptor-Binding Carboxy-Terminal Domain of the Bacteriophage T5 L-Shaped Tail Fibre with and without Its Intra-Molecular Chaperonejournal article10.3390/v71229461999-4915open access