Structural highlights
FunctionTUBE_BPT4 Structural component of the bacteriophage tail which consists of a contractile sheath, a tube and a baseplate. The central cylindrical segment of the tail consists of a rigid tube, composed of multiple copies of gp19, surrounded by the outer contractile sheath assembled from gp18 subunits. During infection, contraction of the sheath drives the central tube through the host outer membrane, creating a channel for DNA ejection from the capsid into the host cell.[1] 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[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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