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Phage T4 neck in post-tail-contraction state (genome-full particle)
Structural highlights
FunctionPORTL_BPT4 Forms the portal vertex of the capsid (PubMed:2685327, PubMed:24126213). 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. Binds to the terminase subunits to form the packaging machine. Attaches to the host inner membrane most likely through interaction with host yidC and forms together with chaperone gp40 an initiator complex to form the prohead.[1] [2] Publication Abstract from PubMedMyophage is endowed with a sophisticated contractile tail and infection machinery. However, the mechanisms of host recognition, signal transduction, and genome delivery remain poorly understood. Here, we capture a pre-genome-release intermediate of myophage T4 and determine its structure by cryo-electron microscopy. Comparative analysis of this tail-contracted, pre-genome-release intermediate structure with the mature T4 virion and the tail-contracted, post-genome-release structure reveals structural transitions in the tail, tape-measure protein (TMP), baseplate, and long tail fibers that drive genome delivery. Our findings further suggest that tail sheath contraction is coupled to a coordinated repositioning of the viral DNA-TMP complex, potentially facilitating genome translocation via charge-mediated interactions. It appears that the expelled TMP may further reorganize into a putative transmembrane complex that supports genome delivery into the host cytosol. Cryo-EM Structures of Phage T4 Infection Intermediate.,Shao Q, Dong J, Wang A, Hu H, Yue J, Li H, Li Y, Zhang Q, Liu J, Sun L, Fokine A, Rao VB, Tao P, Fang Q J Mol Biol. 2026 Jul 4;438(19):169938. doi: 10.1016/j.jmb.2026.169938. PMID:42401366[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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