Structural changes of a bacteriophage upon DNA packaging and maturation

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

“…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).…”

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

“…It is still a puzzle how initially identical subunits adopt both hexameric and pentameric conformations in the capsid and select the correct locations needed to form closed shells of the proper size. Biochemical and genetic studies have shown that the portal is involved in initiation of capsid assembly (Newcomb et al, 2005) and functions akin to a DNA-sensor coupling genome-packaging achieved by a genome-packaging machinery-"terminase complex" (Chen et al, 2020;Yunxiang Yang, 2020) with icosahedral capsid maturation (Lokareddy et al, 2017). Structural investigations of the herpesvirus portal have proven challenging due to the small size of this dodecamer, which accounts for less than 1% of the total mass of the capsid protein layer and the technical difficulties involved in resolving non-icosahedral components of such large icosahedral viruses (diameter is ∼1,250 Å).…”

Progress towards revealing the mechanism of herpesvirus capsid maturation and genome packaging

“…With the advance of cryo-electron microscopy (cryo-EM), the high-resolution structures of herpesvirus capsid (Yu et al, 2017;Wang et al, 2018;Yuan et al, 2018) and the unique portal-vertex (Gong et al, 2019;Liu et al, 2019) of the infectious virion have been determined recently. These results showed that the structures of the herpesvirus major capsid protein and the portal, as well as the interactions among them closely resemble that of the tailed DNA bacteriophage, indicating the herpesvirus shares a common mechanism of the capsid assembly and genome package with the bacteriophage (Yu et al, 2017;Wang et al, 2018;Yuan et al, 2018;Gong et al, 2019;Liu et al, 2019;Chen et al, 2020). Although these achievements greatly advanced our understanding the structures and functions of herpesvirus capsid and portal, there are still questions regarding the herpesvirus capsid assembly and genome package: 1) what's the working mechanism of the herpesvirus terminase?…”