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Cyanophage A4 capsid asymmetric unit
Structural highlights
FunctionPublication Abstract from PubMedUpon infection, the podophages usually eject a couple of proteins from the capsid to form a transmembrane ejectosome on the host cell membrane that facilitates the ejection of viral genome. However, it remains unclear how these proteins of pre-ejectosome are finely assembled at the center of highly packaged genome. Here, we report the intact structure of Anabaena cyanopodophage A4, which consists of a capsid stabilized by two types of cement proteins and a short tail attached with six tail fibers. Notably, we find a pentameric pre-ejectosome at the core of capsid, which is composed of four ejection proteins wrapped into a coaxial cylinder of triple layers. Moreover, a segment of genomic DNA runs along the positively charged circular cleft formed by two ejection proteins. Based on the mortise-and-tenon architecture of pre-ejectosome in combination with previous studies, we propose a putative DNA packaging process and ejection mechanism for podophages. These findings largely enrich our knowledge on the assembly mechanism of podophages, which might facilitate the application of A4 as a chassis cyanophage in synthetic biology. Cryo-EM structure of cyanopodophage A4 reveals a pentameric pre-ejectosome in the double-stabilized capsid.,Hou P, Zhou RQ, Jiang YL, Yu RC, Du K, Gan N, Ke F, Zhang QY, Li Q, Zhou CZ Proc Natl Acad Sci U S A. 2025 Apr 8;122(14):e2423403122. doi: , 10.1073/pnas.2423403122. Epub 2025 Mar 31. PMID:40163721[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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