title: Bacteriophage SPP1 tail tube protein self-assembles into β-structure-rich tubes.
abstract: The majority of known bacteriophages have long tails that serve for bacterial target recognition and viral DNA delivery into the host. These structures form a tube from the viral capsid to the bacterial cell. The tube is formed primarily by a helical array of tail tube protein (TTP) subunits. In phages with a contractile tail, the TTP tube is surrounded by a sheath structure. Here, we report the first evidence that a phage TTP, gp17.1 of siphophage SPP1, self-assembles into long tubes in the absence of other viral proteins. gp17.1 does not exhibit a stable globular structure when monomeric in solution, even if it was confidently predicted to adopt the β-sandwich fold of phage λ TTP. However, Fourier transform infrared and nuclear magnetic resonance spectroscopy analyses showed that its β-sheet content increases significantly during tube assembly, suggesting that gp17.1 acquires a stable β-sandwich fold only after self-assembly. EM analyses revealed that the tube is formed by hexameric rings stacked helicoidally with the same organization and helical parameters found for the tail of SPP1 virions. These parameters were used to build a pseudo-atomic model of the TTP tube. The large loop spanning residues 40-56 is located on the inner surface of the tube, at the interface between adjacent monomers and hexamers. In line with our structural predictions, deletion of this loop hinders gp17.1 tube assembly in vitro and interferes with SPP1 tail assembly during phage particle morphogenesis in bacteria.
authors.affiliation: From the Laboratoire de Biologie Structurale et Radiobiologie, UMR CNRS 8221 and CEA IBITECS, Commissariat à l'Energie Atomique, Saclay 91191 Gif-sur-Yvette Cedex, France.
authors.forename: Chantal
authors.initials: C
authors.lastname: Langlois
authors.affiliation: From the Laboratoire de Biologie Structurale et Radiobiologie, UMR CNRS 8221 and CEA IBITECS, Commissariat à l'Energie Atomique, Saclay 91191 Gif-sur-Yvette Cedex, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Ramboarina
authors.affiliation: the NMR Spectroscopy Group, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands, the Microbiology Department, Tuljaram Chaturchand College, Baramati-413102, India.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Cukkemane
authors.affiliation: the Unité de Virologie Moléculaire et Structurale, CNRS UPR3296, Centre de Recherche de Gif, Bâtiment 14B, CNRS, 91198 Gif-sur-Yvette, France, and.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Auzat
authors.affiliation: From the Laboratoire de Biologie Structurale et Radiobiologie, UMR CNRS 8221 and CEA IBITECS, Commissariat à l'Energie Atomique, Saclay 91191 Gif-sur-Yvette Cedex, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Chagot
authors.affiliation: From the Laboratoire de Biologie Structurale et Radiobiologie, UMR CNRS 8221 and CEA IBITECS, Commissariat à l'Energie Atomique, Saclay 91191 Gif-sur-Yvette Cedex, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Gilquin
authors.affiliation: the Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, United Kingdom.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Ignatiou
authors.affiliation: the Unité de Virologie Moléculaire et Structurale, CNRS UPR3296, Centre de Recherche de Gif, Bâtiment 14B, CNRS, 91198 Gif-sur-Yvette, France, and.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Petitpas
authors.affiliation: From the Laboratoire de Biologie Structurale et Radiobiologie, UMR CNRS 8221 and CEA IBITECS, Commissariat à l'Energie Atomique, Saclay 91191 Gif-sur-Yvette Cedex, France.
authors.forename: Emmanouil
authors.initials: E
authors.lastname: Kasotakis
authors.affiliation: From the Laboratoire de Biologie Structurale et Radiobiologie, UMR CNRS 8221 and CEA IBITECS, Commissariat à l'Energie Atomique, Saclay 91191 Gif-sur-Yvette Cedex, France.
authors.forename: Maïté
authors.initials: M
authors.lastname: Paternostre
authors.affiliation: the Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, United Kingdom.
authors.forename: Helen E
authors.initials: HE
authors.lastname: White
authors.affiliation: the Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, United Kingdom.
authors.forename: Elena V
authors.initials: EV
authors.lastname: Orlova
authors.affiliation: the NMR Spectroscopy Group, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
authors.forename: Marc
authors.initials: M
authors.lastname: Baldus
authors.affiliation: the Unité de Virologie Moléculaire et Structurale, CNRS UPR3296, Centre de Recherche de Gif, Bâtiment 14B, CNRS, 91198 Gif-sur-Yvette, France, and.
authors.forename: Paulo
authors.initials: P
authors.lastname: Tavares
authors.affiliation: From the Laboratoire de Biologie Structurale et Radiobiologie, UMR CNRS 8221 and CEA IBITECS, Commissariat à l'Energie Atomique, Saclay 91191 Gif-sur-Yvette Cedex, France, sophie.zinn@cea.fr.
authors.forename: Sophie
authors.initials: S
authors.lastname: Zinn-Justin
mesh_terms: D000595:Amino Acid Sequence; D001435:Bacteriophages / Q000737:chemistry; D008969:Molecular Sequence Data; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D014764:Viral Proteins / Q000737:chemistry*
chemical_list: D014764:Viral Proteins
keywords: Bacteriophage; Electron Microscopy; Fourier Transform IR (FTIR); Solid State NMR; Tail Tube; Tertiary Structure; Virion; Virus Assembly