Ultrastructure of macromolecular assemblies contributing to bacterial spore resistance revealed by in situ cryo-electron tomography - Groupe Microscopie Electronique et Méthodes / Methods and Electron Microscopy Group (IBS-MEM)
Article Dans Une Revue Nature Communications Année : 2024

Ultrastructure of macromolecular assemblies contributing to bacterial spore resistance revealed by in situ cryo-electron tomography

Elda Bauda
Benoit Gallet
Jana Moravcova
  • Fonction : Auteur
Gregory Effantin
Helena Chan
  • Fonction : Auteur
Jiri Novacek
Christopher D A Rodrigues
Guy Schoehn
Cécile Morlot
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Résumé

Bacterial spores owe their incredible resistance capacities to molecular structures that protect the cell content from external aggressions. Among the determinants of resistance are the quaternary structure of the chromosome and an extracellular shell made of proteinaceous layers (the coat), the assembly of which remains poorly understood. Here, in situ cryo-electron tomography on lamellae generated by cryo-focused ion beam micromachining provides insights into the ultrastructural organization of Bacillus subtilis sporangia. The reconstructed tomograms reveal that early during sporulation, the chromosome in the forespore adopts a toroidal structure harboring 5.5-nm thick fibers. At the same stage, coat proteins at the surface of the forespore form a stack of amorphous or structured layers with distinct electron density, dimensions and organization. By analyzing mutant strains using cryo-electron tomography and transmission electron microscopy on resin sections, we distinguish seven nascent coat regions with different molecular properties, and propose a model for the contribution of coat morphogenetic proteins.
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hal-04747048 , version 1 (21-10-2024)

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Elda Bauda, Benoit Gallet, Jana Moravcova, Gregory Effantin, Helena Chan, et al.. Ultrastructure of macromolecular assemblies contributing to bacterial spore resistance revealed by in situ cryo-electron tomography. Nature Communications, 2024, 15 (1), pp.1376. ⟨10.1038/s41467-024-45770-6⟩. ⟨hal-04747048⟩
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