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The asymmetric unit of P22 empty capsid
Structural highlights
FunctionCAPSD_BPP22 Assembles to form an icosahedral capsid with a T=7 symmetry. Publication Abstract from PubMedThe formation of many double-stranded DNA viruses, such as herpesviruses and bacteriophages, begins with the scaffolding-protein-mediated assembly of the procapsid. Subsequently, the procapsid undergoes extensive structural rearrangement and expansion to become the mature capsid. Bacteriophage P22 is an established model system used to study virus maturation. Here, we report the cryo-electron microscopy structures of procapsid, empty procapsid, empty mature capsid, and mature capsid of phage P22 at resolutions of 2.6 A, 3.9 A, 2.8 A, and 3.0 A, respectively. The structure of the procapsid allowed us to build an accurate model of the coat protein gp5 and the C-terminal region of the scaffolding protein gp8. In addition, interactions among the gp5 subunits responsible for procapsid assembly and stabilization were identified. Two C-terminal alpha-helices of gp8 were observed to interact with the coat protein in the procapsid. The amino acid interactions between gp5 and gp8 in the procapsid were consistent with the results of previous biochemical studies involving mutant proteins. Our structures reveal hydrogen bonds and salt bridges between the gp5 subunits in the procapsid and the conformational changes of the gp5 domains involved in the closure of the local sixfold opening and a thinner capsid shell during capsid maturation. Assembly and Capsid Expansion Mechanism of Bacteriophage P22 Revealed by High-Resolution Cryo-EM Structures.,Xiao H, Zhou J, Yang F, Liu Z, Song J, Chen W, Liu H, Cheng L Viruses. 2023 Jan 26;15(2):355. doi: 10.3390/v15020355. PMID:36851569[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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