Structures of T7 bacteriophage portal and tail suggest a viral DNA retention and ejection mechanism
Surface representation of the PDB corresponding to the structure of the Tail Complex of phage T7 solved at 3,6 A resolution using cryo-electron microscopy. The 1,5 MDa complex is built by 12 chains of gp12 (portal), 12 chains of gp11 (adaptor) and 6 chains of gp12 (nozzle).
Cuervo A, Fabrega-Ferrer M, Machon C, Conesa JJ, Fernandez FJ, Perez-Luque R, Perez-Ruiz M, Pous J, Vega MC, Carrascosa JL, Coll M.
Nat Commun 2019 Aug; 10: 3746.
Double-stranded DNA bacteriophages package their genome at high pressure inside a procapsid through the portal, an oligomeric ring protein located at a unique capsid vertex. Once the DNA has been packaged, the tail components assemble on the portal to render the mature infective virion. The tail tightly seals the ejection conduit until infection, when its interaction with the host membrane triggers the opening of the channel and the viral genome is delivered to the host cell. Using high-resolution cryo-electron microscopy and X-ray crystallography, here we describe various structures of the T7 bacteriophage portal and fiber-less tail complex, which suggest a possible mechanism for DNA retention and ejection: a portal closed conformation temporarily retains the genome before the tail is assembled, whereas an open portal is found in the tail. Moreover, a fold including a seven-bladed beta-propeller domain is described for the nozzle tail protein.
PubMed: 31431626. Doi: 10.1038/s41467-019-11705-9. OPEN Free PMC
Additional Information
The following article about the same system has been also published in August 2019 by Carrascosa, Coll and coworkers:
Atomic structure of the Epstein-Barr virus portal. Machón C, Fàbrega-Ferrer M, Zhou D, Cuervo A, Carrascosa JL, Stuart DI, Coll M., Nat Commun 2019 Aug; 10: 3891.
PubMed: 31467275. Doi: 10.1038/s41467-019-11706-8. OPEN Free PMC
