{
  "id": 4039646,
  "title": "In-Cell Protein Crystallization via a Locally Flexible 24-mer Assembly Precursor",
  "url": "https://urgent.news/2026/08/28/in-cell-protein-crystallization-via-a-locally-flexible-24-mer",
  "topic": "science",
  "section": "Science",
  "published": "2026-08-28T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.08.25.746898v1?rss=1"
  },
  "original_language": "en",
  "account": "In-cell protein crystallization (ICPC) is a process that creates well-ordered protein crystals within living cells, yet the methods proteins utilize to achieve long-range crystalline order within the cellular setting are not fully understood. This study identifies the assembly process of CipB, a protein that forms crystals in Photorhabdus luminescens. Upon crystallization within cells, CipB crystals break down in mildly acidic conditions, revealing a dominant 24-mer species, which suggests that a specific 24-mer assembly precursor is central to in-cell crystal formation.\n\nStructural studies of the recrystallized CipB protein show that the same 24-mer arrangement forms a body-centered cubic lattice, mirroring the lattice structure of the in-cell crystals. Cryo-electron microscopy (cryo-EM) and molecular dynamics simulations reveal that the 24-mer precursor maintains its overall structure while allowing for local flexibility at the N-terminal and surface-loop regions. Additionally, mutation studies establish a connection between the N-terminal region and the formation of the 24-mer precursor, and between surface residues and the organization of these precursors into the lattice assembly.\n\nThese findings support a stepwise crystallization model, where the N-terminal flexibility plays a crucial role in the formation of the assembly-competent 24-mer precursor, while specific hydrophobic surface interactions subsequently arrange these precursors into a long-range-ordered crystalline lattice.",
  "summary": "In-cell protein crystallization (ICPC) produces ordered protein crystals within living cells, but the mechanisms used by proteins to acquire long-range crystalline order in the cellular environment remains poorly understood. Here, we define the assembly pathway of CipB, a crystalline inclusion protein from Photorhabdus luminescens. CipB crystals formed in cells dissolve under mild acidic…",
  "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."
}