Structures of the portal vertex reveal essential protein-protein interactions for Herpesvirus assembly and maturation

Abstract

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Architecture of the herpesvirus genome-packaging complex and implications for DNA translocation

“…Yunxiang Yang et al hexameric structures of the herpesvirus terminase complex with the central channel bigger (39 Å in diameter) than the diameter of the B-form dsDNA (∼20 Å in diameter) favors the revolution model, which is consistent with the internal diameter of the herpesvirus portal (∼36 Å in diameter) (Nan Wang et al, 2020) (Fig. 4A and 4B).…”

“…1E). Expectedly, the central channel of the hexameric ring has a similar internal diameter to that of the dodecameric portal in herpesviruses (Nan Wang et al, 2020), also suggesting the role in dsDNA translocation. Each subunit of the hexameric ring is a heterotrimer formed by three proteins (pUL15, pUL28 and pUL33) interdigitating with each other (Fig.…”

“…4D). Immediately prior to completion of packaging, head-full signal sensed by the capsid proteins and relayed through the portal (Nan Wang et al, 2020) triggers pUL15 to undergo a regulator mediated domain rearrangement of the nuclease, converting the terminase complex to the cleavage mode (Fig. 4D).…”

“…To further improve resolution we used the block-based reconstruction (Wang et al, 2018;Yuan et al, 2018;Zhu et al, 2018a;Wang et al, 2019). The orientation parameters of each particle image (hexamer and dodecamer) determined in Relion were used to guide extraction of the block region (∼50% bigger than monomer) and the block was refined and reconstructed (Scheres, 2012).…”

“…The terminase complex recognizes a specific sequence or structure on the concatemeric DNA and cuts it to produce the free end where packaging is initiated (Mettenleiter et al, 2009). Acting as the packaging motor, the terminase complex then hydrolyzes ATP molecules to translocate negatively charged DNA into a space-limited procapsid through a dodecameric portal (Chen, 2020;Nan Wang, et al 2020) (Fig. 1A).…”