{
  "abstract": "Viruses that infect bacteria, termed bacteriophages or phages, typically encode their own DNA replication machinery that rapidly generates many copies of the phage genomic DNA in an infected cell. Nucleus-forming phages of the chimallivirus family possess a distinctive repertoire of predicted DNA replication proteins, with two proteins annotated as DNA polymerases plus a DnaB-like replicative helicase, but lacking an identified primase or sliding clamp protein. Here, we demonstrate that in the Pseudomonas aeruginosa-infecting chimallivirus PhiKZ, the core DNA polymerase comprises a stable 1:1 complex of two DNA polymerase subunits, termed DNAPN and DNAPC. A 2.1 A resolution cryoelectron microscopy structure of this core complex reveals homology to other phage and bacterial B-family DNA polymerases. Next, we identify a direct but transient interaction between the core DNA polymerase complex and a third protein termed Rhc, which possesses an N-terminal RNase H domain and a C-terminal domain related to DNA sliding clamp proteins. Cryoelectron microscopy structures of a stabilized DNA polymerase-Rhc complex, and of this complex bound to a primer-template DNA, reveal a single Rhc subunit that cooperates with the DNA polymerase thumb domain to bind double-stranded DNA emerging from the DNA polymerase active site. While the Rhc RNase H domain is not resolved in our structures, this domain is situated such that it could degrade RNA associated with an incoming template DNA strand. In vitro primer-extension assays show that Rhc strongly boosts DNA polymerase activity, and that this boost relies on the Rhc-DNA polymerase interface we observe in our structures. Overall, our findings reveal a distinctive chimallivirus-specific DNA replication machine with an integrated DNA-binding subunit related to sliding clamp proteins, and a flexibly-linked RNase H domain.",
  "abstract_shown": true,
  "affiliations": [
    "University of California, San Diego"
  ],
  "article_type": "New results",
  "arxiv": null,
  "author_total": 6,
  "authors": [
    {
      "name": "D. Basu"
    },
    {
      "name": "R. K. Min"
    },
    {
      "name": "K. Inlow"
    },
    {
      "name": "J. Pogliano"
    },
    {
      "name": "E. Villa"
    },
    {
      "affs": [
        0
      ],
      "name": "K. D. Corbett"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/cz8dnjh43wgv0.bib",
  "cited_by": 0,
  "doi": "10.64898/2026.09.30.755723",
  "fulltext_url": "https://www.biorxiv.org/content/10.64898/2026.09.30.755723v1.full",
  "id": "cz8dnjh43wgv0",
  "issns": [],
  "landing_url": "https://www.biorxiv.org/content/10.64898/2026.09.30.755723v1",
  "language": null,
  "licence": "CC-BY-NC-ND",
  "licence_label": "CC BY-NC-ND",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "biorxiv",
      "biochemistry"
    ],
    [
      "openalex",
      "2303|Bacteriophages and microbial interactions"
    ]
  ],
  "openalex": "W7216077003",
  "pdf_url": "https://www.biorxiv.org/content/10.64898/2026.09.30.755723v1.full.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-30",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/cz8dnjh43wgv0.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:46Z",
      "native_id": "10.64898/2026.09.30.755723",
      "source": "biorxiv",
      "url": "https://www.biorxiv.org/content/10.64898/2026.09.30.755723v1"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "openalex:2303|Bacteriophages and microbial interactions",
      "subfield": "ecology"
    }
  ],
  "title": "A bacteriophage split DNA polymerase incorporates a sliding clamp-derived processivity subunit",
  "title_text": "A bacteriophage split DNA polymerase incorporates a sliding clamp-derived processivity subunit",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:46Z",
  "url": "https://research.draconitic.com/paper/cz8dnjh43wgv0",
  "venue": "bioRxiv",
  "versions": []
}