Ultrastructure of macromolecular assemblies contributing to bacterial spore resistance revealed by in situ cryo-electron tomography - Archive ouverte HAL Access content directly
Journal Articles Nature Communications Year : 2024

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

Elda Bauda
Benoit Gallet
Jana Moravcova
  • Function : Author
Gregory Effantin
Helena Chan
  • Function : Author
Jiri Novacek
Pierre-Henri Jouneau
Christopher Rodrigues
Guy Schoehn
Christine Moriscot
Cécile Morlot

Abstract

Abstract 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.

Dates and versions

hal-04462524 , version 1 (16-02-2024)

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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-04462524⟩
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