{
  "id": 14976394,
  "title": "Evolution of histone mRNA 3' end processing machinery in eukaryotes",
  "url": "https://urgent.news/2026/10/16/evolution-of-histone-mrna-3-end-processing-machinery-in-eukaryotes",
  "topic": "science",
  "section": "Science",
  "published": "2026-10-16T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.10.14.759114v1?rss=1"
  },
  "original_language": "en",
  "account": "Replication-dependent histone mRNAs in metazoans terminate with a conserved 3' stem-loop recognized by SLBP and processed by a unique U7 snRNP-dependent cleavage system. Outside animals, the origins of this pathway are unclear, and fungi and many plants were thought to have abandoned SLBP-dependent histone mRNA processing entirely. Researchers have now analyzed extensive homology searches, structural data, and genome-wide mapping of histone 3' features in eukaryotes to trace the evolution of histone mRNA processing machinery. The study reveals that SLBP, stem-loop motifs, and several U7-associated factors are more prevalent across eukaryotes than previously thought, challenging the notion of widespread loss outside metazoans. In fact, early-diverging fungal lineages still possess SLBP orthologs with conserved RNA-binding domains, stem-loop motifs, and extra pathway components. As fungi evolved, there was a trend toward replacing SL-associated processing elements with polyadenylation-associated features. Even with minimal U7-associated machinery, early-diverging fungi still have noncanonical poly(A) polymerases alongside SLBP and stem-loop motifs, indicating a potential intermediate state in histone mRNA 3' processing evolution. These findings support a gradual shift from an ancestral SLBP/stem-loop-dependent histone mRNA processing system to the modern polyadenylation mechanism, providing a revised timeline for the development of histone mRNA 3' end formation in eukaryotes.",
  "summary": "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…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}