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The cryo-EM structure of the collar complex and tail axis in bacteriophage phi29
Structural highlights
Function[PORTL_BPPH2] Forms the portal vertex of the capsid (PubMed:10801350) (PubMed:19744688, PubMed:21570409). This portal plays critical roles in head assembly, genome packaging, neck/tail attachment, and genome ejection (By similarity). The portal protein multimerizes as a single ring-shaped homododecamer arranged around a central channel (PubMed:11812138, PubMed:21570409). Binds to the 6 packaging RNA molecules (pRNA) forming a double-ring structure which in turn binds to the ATPase gp16 hexamer, forming the active DNA-translocating motor (PubMed:15886394, PubMed:11130079). This complex is essential for the specificity of packaging from the left DNA end.[UniProtKB:P13334][1] [2] [3] [4] [5] [6] [FIB12_BPPH2] Structural component of the 12 appendages that hang from the lower collar. Adhesion protein that binds to the host cell surface during virus attachment and mediates teichoic acids degradation.[7] [TUB11_BPPH2] Forms the proximal part of the tail tube.[8] 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[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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