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Cryo-EM structure of T7 bacteriophage portal protein, 12mer, open valve
Structural highlights
Function[PORTL_BPT7] Forms the portal vertex of the capsid. This portal plays critical roles in head assembly, genome packaging, neck/tail attachment, and genome ejection. The portal protein multimerizes as a single ring-shaped homododecamer arranged around a central channel.[HAMAP-Rule:MF_04120][1] [2] Publication Abstract from PubMedDouble-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. Structures of T7 bacteriophage portal and tail suggest a viral DNA retention and ejection mechanism.,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 20;10(1):3746. doi: 10.1038/s41467-019-11705-9. PMID:31431626[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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