The flagellotropic bacteriophage YSD1 targets Salmonella Typhi with a Chi‐like protein tail fibre

• Published in: Molecular microbiology 2019-12, Vol.112 (6), p.1831-1846
• Main Authors: Dunstan, Rhys A., Pickard, Derek, Dougan, Sam, Goulding, David, Cormie, Claire, Hardy, Joshua, Li, Fuyi, Grinter, Rhys, Harcourt, Katherine, Yu, Lu, Song, Jiangning, Schreiber, Fernanda, Choudhary, Jyoti, Clare, Simon, Coulibaly, Fasseli, Strugnell, Richard A., Dougan, Gordon, Lithgow, Trevor
• Format: Article
• Language: English
• Subjects: Antibodies; Antigens; Electron micrographs; Flagella; Flagellin; Gene sequencing; Genomes; Host range; Labeling; Phages; Proteins; Salmonella; Waterways
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/mmi.14396

Summary The discovery of a Salmonella‐targeting phage from the waterways of the United Kingdom provided an opportunity to address the mechanism by which Chi‐like bacteriophage (phage) engages with bacterial flagellae. The long tail fibre seen on Chi‐like phages has been proposed to assist the phage particle in docking to a host cell flagellum, but the identity of the protein that generates this fibre was unknown. We present the results from genome sequencing of this phage, YSD1, confirming its close relationship to the original Chi phage and suggesting candidate proteins to form the tail structure. Immunogold labelling in electron micrographs revealed that YSD1_22 forms the main shaft of the tail tube, while YSD1_25 forms the distal part contributing to the tail spike complex. The long curling tail fibre is formed by the protein YSD1_29, and treatment of phage with the antibodies that bind YSD1_29 inhibits phage infection of Salmonella. The host range for YSD1 across Salmonella serovars is broad, but not comprehensive, being limited by antigenic features of the flagellin subunits that make up the Salmonella flagellum, with which YSD1_29 engages to initiate infection. Bacteriophages can recognise a wide variety of receptors on the surface of their bacterial hosts. We have isolated a novel Chi‐like bacteriophage, YSD1, capable of targeting the bacterial flagella using a long thin fibre emanating from the end of the phage tail. The protein that forms this tail fibre has been identified and the targeting of different flagella types by this phage has been characterised.