{
  "abstract": "Replication-dependent histone mRNAs in metazoans terminate in a conserved 3' stem-loop (SL) recognized by stem-loop binding protein (SLBP) and processed by a specialized U7 snRNP-dependent cleavage machinery. Outside animals, the evolutionary history of this pathway remains poorly resolved, and fungi and most plants are widely thought to have lost SLBP-SL-dependent histone mRNA processing entirely. Here, we combine large-scale homology searches, structural and domain analyses, and genome-wide mapping of histone 3'-end features across eukaryotes to reconstruct the evolution of histone mRNA processing machinery. We show that SLBP, stem-loop motifs and multiple U7-associated factors are far more broadly distributed across eukaryotes than previously appreciated, revising earlier models of widespread loss outside metazoans. Contrary to prevailing views, early-diverging fungal lineages retain SLBP orthologs with conserved RNA-binding domains, stem-loop motifs and additional components of the canonical pathway. Across fungi, we identify a clade-wise shift from SL-associated processing features toward canonical polyadenylation-associated features. Early-diverging fungi retain noncanonical poly(A) polymerases alongside SLBP and stem-loop motifs despite sparse U7-associated machinery, consistent with a previously unrecognized intermediate state in histone mRNA 3'-end processing. Our results support a stepwise evolutionary transition from ancestral SLBP/stem-loop-associated histone mRNA processing to canonical polyadenylation and provide a revised framework for the evolution of histone mRNA 3'-end formation in eukaryotes.",
  "abstract_shown": true,
  "affiliations": [
    "Trinity College Dublin"
  ],
  "article_type": "New results",
  "arxiv": null,
  "author_total": 3,
  "authors": [
    {
      "name": "B. Zhao"
    },
    {
      "name": "U. M. Bond"
    },
    {
      "affs": [
        0
      ],
      "name": "M. Ni Leathlobhair"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/ar2x2azwzvrt0.bib",
  "cited_by": 0,
  "doi": "10.64898/2026.10.14.759114",
  "fulltext_url": "https://www.biorxiv.org/content/10.64898/2026.10.14.759114v1.full",
  "id": "ar2x2azwzvrt0",
  "issns": [],
  "landing_url": "https://www.biorxiv.org/content/10.64898/2026.10.14.759114v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "biorxiv",
      "evolutionary biology"
    ],
    [
      "openalex",
      "1312|RNA Research and Splicing"
    ]
  ],
  "openalex": "W7222490300",
  "pdf_url": "https://www.biorxiv.org/content/10.64898/2026.10.14.759114v1.full.pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-14",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/ar2x2azwzvrt0.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:28:09Z",
      "native_id": "10.64898/2026.10.14.759114",
      "source": "biorxiv",
      "url": "https://www.biorxiv.org/content/10.64898/2026.10.14.759114v1"
    }
  ],
  "subjects": [
    {
      "field": "biology",
      "origin": "biorxiv:evolutionary biology",
      "subfield": "evolutionary-biology"
    }
  ],
  "title": "Evolution of histone mRNA 3' end processing machinery in eukaryotes",
  "title_text": "Evolution of histone mRNA 3' end processing machinery in eukaryotes",
  "type": "preprint",
  "updated_at": "2026-10-30T12:28:09Z",
  "url": "https://research.draconitic.com/paper/ar2x2azwzvrt0",
  "venue": "bioRxiv",
  "versions": []
}