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J Biol Chem. 2015 Feb 6;290(6):3836-49. doi: 10.1074/jbc.M114.613166. Epub 2014 Dec 17.

Bacteriophage SPP1 tail tube protein self-assembles into β-structure-rich tubes.

Author information

1
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.
2
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.
3
the Unité de Virologie Moléculaire et Structurale, CNRS UPR3296, Centre de Recherche de Gif, Bâtiment 14B, CNRS, 91198 Gif-sur-Yvette, France, and.
4
the Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, United Kingdom.
5
the NMR Spectroscopy Group, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
6
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.

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.

KEYWORDS:

Bacteriophage; Electron Microscopy; Fourier Transform IR (FTIR); Solid State NMR; Tail Tube; Tertiary Structure; Virion; Virus Assembly

PMID:
25525268
PMCID:
PMC4319047
DOI:
10.1074/jbc.M114.613166
[Indexed for MEDLINE]
Free PMC Article

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