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

  • Cell. 2025 Dec 29:S0092-8674(25)01376-5. doi: 10.1016/j.cell.2025.11.041.
Zishuo Yu  1 ,  Pradeep Sathyanarayana  2 ,  Cong Liu  3 ,  Joel M J Tan  4 ,  Pan Yang  1 ,  Biswajit Das  1 ,  Side Hu  1 ,  Xiaoyi Fan  1 ,  Chenggong Ji  1 ,  Sandra K Weller  5 ,  Mrinal Shekhar  3 ,  Donald M Coen  2 ,  Philip J Kranzusch  4 ,  Joseph J Loparo  6 ,  Jonathan Abraham  7
Affiliations
  • 1. Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
  • 2. Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
  • 3. Center for the Development of Therapeutics, Broad Institute of Harvard and MIT, Cambridge, MA, USA.
  • 4. Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA; Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA, USA.
  • 5. Department of Molecular Biology and Biophysics, University of Connecticut School of Medicine, Farmington, CT, USA.
  • 6. Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA. Electronic address: [email protected].
  • 7. Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA; Department of Medicine, Division of Infectious Diseases, Brigham and Women's Hospital, Boston, MA, USA; Center for Integrated Solutions for Infectious Diseases, Broad Institute of Harvard and MIT, Cambridge, MA, USA; Howard Hughes Medical Institute, Boston, MA, USA. Electronic address: [email protected].
PMID: 41468884 DOI: 10.1016/j.cell.2025.11.041
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-electron microscopy (cryo-EM) structures of the herpes simplex virus 1 H/P complex bound to HPIs, showing that these lock the H/P complex in an inactive state. Single-molecule assays reveal that HPIs cause H/P 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 the 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.

Keywords
DNA replication; antiviral; helicase; herpesvirus; polymerase; primase.
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