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Cryo-EM of capsid of bacteriophage ChiCryo-EM of capsid of bacteriophage Chi
Structural highlights
FunctionM9NUS8_9CAUD Assembles to form an icosahedral capsid. The assembly is primed by the interaction between capsid assembly protease and portal dodecamer, and major capsid proteins assemble cooperatively to form the procapsid with the help of capsid scaffolding protein. Major capsid protein forms hexons and pentons of the icosahedron. Viral genomic DNA is packaged into the procapsid through the portal vertex. The packaging triggers a dramatic reconfiguration of the capsid shell.[HAMAP-Rule:MF_04133] Publication Abstract from PubMedThe flagellotropic bacteriophage chi (Chi) infects bacteria via the flagellar filament. Despite years of study, its structural architecture remains partly characterized. Through cryo-EM, we unveil chi's nearly complete structure, encompassing capsid, neck, tail, and tail tip. While the capsid and tail resemble phage YSD1, the neck and tail tip reveal new proteins and their arrangement. The neck shows a unique conformation of the tail tube protein, forming a socket-like structure for attachment to the neck. The tail tip comprises four proteins, including distal tail protein (DTP), two baseplate hub proteins (BH1P and BH2P), and tail tip assembly protein (TAP) exhibiting minimal organization compared to other siphophages. Deviating from the consensus in other siphophages, DTP in chi forms a trimeric assembly, reducing tail symmetry from 6-fold to 3-fold at the tip. These findings illuminate the previously unexplored structural organization of chi's neck and tail tip. Cryo-EM structure of flagellotropic bacteriophage Chi.,Sonani RR, Esteves NC, Scharf BE, Egelman EH Structure. 2024 Jul 11;32(7):856-865.e3. doi: 10.1016/j.str.2024.03.011. Epub , 2024 Apr 12. PMID:38614087[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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