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The cryo-EM structure of bacteriophage phi29 prohead
Structural highlights
Function[CAPSD_BPPH2] Assembles to form a prolate capsid shell of about 54 nm in length and 45 nm in width, with a T=3, Q=5 symmetry.[1] [2] [3] [CAPSF_BPPH2] Protein that forms the 55 capsid fibers. These fibers are not always present and may have been lost in some lab strains. They may enhance the attachment of the virions onto the host cell wall.[4] Publication Abstract from PubMedThe mature virion of the tailed bacteriophage varphi29 is an ~33 MDa complex that contains more than 450 subunits of seven structural proteins assembling into a prolate head and a short non-contractile tail. Here, we report the near-atomic structures of the varphi29 pre-genome packaging head (prohead), the mature virion and the genome-emptied virion. Structural comparisons suggest local rotation or oscillation of the head-tail connector upon DNA packaging and release. Termination of the DNA packaging occurs through pressure-dependent correlative positional and conformational changes in the connector. The funnel-shaped tail lower collar attaches the expanded narrow end of the connector and has a 180-A long, 24-strand beta barrel narrow stem tube that undergoes conformational changes upon genome release. The appendages form an interlocked assembly attaching the tail around the collar. The membrane active long loops at the distal end of the tail knob exit during the late stage of infection and form the cone-shaped tip of a largely hydrophobic helix barrel, prepared for membrane penetration. Structural assembly of the tailed bacteriophage varphi29.,Xu J, Wang D, Gui M, Xiang Y Nat Commun. 2019 May 30;10(1):2366. doi: 10.1038/s41467-019-10272-3. PMID:31147544[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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