Download MendeleyStructural insights into HSV-1 origin unwinding by the viral proteins UL9 and ICP8.
Baranovskiy, A.G., Morstadt, L.M., Romero, E.E., Babayeva, N.D., Tahirov, T.H.(2026) Nucleic Acids Res 54
- PubMed: 42283126 Search on PubMedSearch on PubMed Central
- DOI: https://doi.org/10.1093/nar/gkag580
- Primary Citation Related Structures:
9ZGF - PubMed Abstract:
Herpes simplex virus type 1 (HSV-1) causes lifelong infections in human cells and is associated with a range of diseases. HSV-1 DNA replication requires seven viral proteins, including the major DNA-binding protein ICP8, the origin-binding protein UL9, and proteins that comprise the helicase-primase and DNA polymerase complexes. UL9 functions as a DNA helicase that specifically recognizes and binds to the viral origins of replication, OriS and OriL. Here we report the cryo-EM structure of the UL9/ICP8/DNA/ATPγS complex at an overall resolution of 3.18 Å. This structure revealed that UL9 employs an α-helix to separate the DNA strands and captures the initial step of OriS unwinding, in which the C-terminal domain of UL9 specifically binds to the major groove of a DNA double helix, while the N-terminal helicase domain engages the unwound leading and lagging strands. ICP8 interacts with the extreme C-terminal region of UL9, preventing UL9 dimerization. Simultaneously, it binds and stabilizes the leading-strand DNA adjacent to UL9. Together, these findings provide mechanistic insight into UL9-driven DNA unwinding and the cooperative action of UL9 and ICP8 at HSV-1 replication origins, establishing a structural framework for the rational interpretation of prior biochemical data and for the design of new antiviral drugs.
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, United States.
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