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bioRxiv · 10.64898/2025.12.23.696259

Mechanisms of HSV-1 helicase-primase inhibition and replication fork complex assembly

Yu, Z.·Sathyanarayana, P.·Lui, C.·Yang, P.·Weller, S. K.·Shekhar, M.·Coen, D. M.·Loparo, J.·Abraham, J.
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Abstract

Herpesviruses are widespread double-stranded DNA viruses that establish lifelong latency and cause various diseases. Although DNA polymerase-targeting antivirals are effective, increasing drug resistance underscores the need for alternatives. Helicase-primase inhibitors (HPIs) are promising antivirals, but their mechanisms of action are poorly defined. Furthermore, how the helicase-primase (H/P) complex and DNA polymerase coordinate genome replication is not well understood for herpesviruses. Here, we report cryo-EM structures of the herpes simplex virus (HSV) H/P complex bound to HPIs, showing that these lock the helicase-primase complex in an inactive conformation. Single-molecule assays reveal that HPIs cause helicase-primase complexes to pause in unwinding activity on DNA. The structure of an HPI-bound replication fork complex, comprising the H/P complex (UL5, UL52, and UL8) and polymerase holoenzyme (UL30 and UL42), reveals a previously uncharacterized interface bridging these complexes. These findings provide a structural framework for understanding herpesvirus replisome assembly and advancing inhibitor development.

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Yu, Z., Sathyanarayana, P., Lui, C., Yang, P., Weller, S. K., Shekhar, M., Coen, D. M., Loparo, J., Abraham, J.. 2025-12-24. Mechanisms of HSV-1 helicase-primase inhibition and replication fork complex assembly. https://doi.org/10.64898/2025.12.23.696259

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