1.K.5.  The Marine Podoiurus Phage P-SSP7 Nozzel Complex (P-SSP7 Nozzel) Family

Podovirus P-SSP7 infects Prochlorococcus marinus, the most abundant oceanic photosynthetic microorganism. Single-particle cryo-EM yielded icosahedral and asymmetrical structures of infectious P-SSP7 with 4.6-Å and 9-Å resolution, respectively (Liu et al. 2010). The asymmetric reconstruction revealed how symmetry mismatches are accommodated among five of the gene products at the portal vertex. Reconstructions of infectious and empty particles showed a conformational change of the 'valve' density in the nozzle, an orientation difference in the tail fibers, a disordering of the C terminus of the portal protein and the disappearance of the core proteins. In addition, cryo-EM of P-SSP7 infecting Prochlorococcus showed the same tail-fiber conformation as that in empty particles. These observations suggest a mechanism whereby, upon binding to the host cell, the tail fibers induce a cascade of structural alterations of the portal vertex complex that triggers DNA release (Liu et al. 2010).



Liu, X., Q. Zhang, K. Murata, M.L. Baker, M.B. Sullivan, C. Fu, M.T. Dougherty, M.F. Schmid, M.S. Osburne, S.W. Chisholm, and W. Chiu. (2010). Structural changes in a marine podovirus associated with release of its genome into Prochlorococcus. Nat Struct Mol Biol 17: 830-836.


TC#NameOrganismal TypeExample

The marine podoviurus (phage) P-SSP7 nozzel complex including gp12 (the nozzel) and gp11 (the adaptor). gp12 is 192 aas long, and 6 copies are present in a 6x symmetry. gp11 is 204 aas long and has 12 copies in a 6x symmetry. See the family description for details (Liu et al. 2010).

gp12, 192 aas, Q58N56
gp11, 204 aas, Q58N29


Protein FG37_gp075 of Escherichia phage FFH2

Protein FG37_gp075 of Escherichia phage FFH2