title: Visualizing Adsorption of Cyanophage P-SSP7 onto Marine Prochlorococcus.
abstract: Marine cyanobacteria perform roughly a quarter of global carbon fixation, and cyanophages that infect them liberate some of this carbon during infection and cell lysis. Studies of the cyanobacterium Prochlorococcus MED4 and its associated cyanophage P-SSP7 have revealed complex gene expression dynamics once infection has begun, but the initial cyanophage-host interactions remain poorly understood. Here, we used single particle cryo-electron tomography (cryo-ET) to investigate cyanophage-host interactions in this model system, based on 170 cyanophage-to-host adsorption events. Subtomogram classification and averaging revealed three main conformations characterized by different angles between the phage tail and the cell surface. Namely, phage tails were (i) parallel to, (ii) ~45 degrees to, or (iii) perpendicular to the cell surface. Furthermore, different conformations of phage tail fibers correlated with the aforementioned orientations of the tails. We also observed density beyond the tail tip in vertically-oriented phages that had penetrated the cell wall, capturing the final stage of adsorption. Together, our data provide a quantitative characterization of the orientation of phages as they adsorb onto cells, and suggest that cyanophages that abut their cellular targets are only transiently in the "perpendicular" orientation required for successful infection.
authors.affiliation: National Center for Macromolecular Imaging, Verna and Marrs McLean Dept. of Biochemistry &Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA.|National Institute for Physiological Sciences, 38 Nishigonaka, Myodaiji, Okazaki, Aichi, 444-8585, Japan.
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Murata
authors.affiliation: National Center for Macromolecular Imaging, Verna and Marrs McLean Dept. of Biochemistry &Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA.|School of Life Sciences, State Key Lab for Biocontrol, Sun Yat-Sen University, Guangzhou, 510275, P. R. China.
authors.forename: Qinfen
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: National Center for Macromolecular Imaging, Verna and Marrs McLean Dept. of Biochemistry &Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA.
authors.forename: Jesús
authors.initials: J
authors.lastname: Gerardo Galaz-Montoya
authors.affiliation: National Center for Macromolecular Imaging, Verna and Marrs McLean Dept. of Biochemistry &Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA.
authors.forename: Caroline
authors.initials: C
authors.lastname: Fu
authors.affiliation: Department of Civil and Environmental Engineering, M.I.T., Cambridge, MA, 02139, USA.
authors.forename: Maureen L
authors.initials: ML
authors.lastname: Coleman
authors.affiliation: Department of Civil and Environmental Engineering, M.I.T., Cambridge, MA, 02139, USA.
authors.forename: Marcia S
authors.initials: MS
authors.lastname: Osburne
authors.affiliation: National Center for Macromolecular Imaging, Verna and Marrs McLean Dept. of Biochemistry &Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Schmid
authors.affiliation: Department of Civil and Environmental Engineering, M.I.T., Cambridge, MA, 02139, USA.
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Sullivan
authors.affiliation: Department of Civil and Environmental Engineering, M.I.T., Cambridge, MA, 02139, USA.
authors.forename: Sallie W
authors.initials: SW
authors.lastname: Chisholm
authors.affiliation: National Center for Macromolecular Imaging, Verna and Marrs McLean Dept. of Biochemistry &Molecular Biology, Baylor College of Medicine, Houston, TX, 77030, USA.
authors.forename: Wah
authors.initials: W
authors.lastname: Chiu
mesh_terms: D001435:Bacteriophages / Q000648:ultrastructure*; D048929:Prochlorococcus / Q000648:ultrastructure* / Q000821:virology*; D053585:Virus Attachment