9N0B

Cryo-EM of spore appendage from Anaerovoracaceae

Summary for 9N0B

• Entry DOI: 10.2210/pdb9n0b/pdb
• EMDB information: 48780
• Descriptor: spore filament protein subunit (1 entity in total)
• Functional Keywords: spore appendage, helical filament, protein polymer, helical, protein fibril
• Biological source: Bacillota bacterium
• Total number of polymer chains: 9
• Total formula weight: 118643.52

Authors

Bellis, N.F.,Baquero, D.P.,Egelman, E.H.,Krupovic, M.,Wang, F. (deposition date: 2025-01-23, release date: 2025-09-03)

Primary citation

Sleutel, M.,Sogues, A.,Van Gerven, N.,Jonsmoen, U.L.,Van Molle, I.,Fislage, M.,Theunissen, L.D.,Bellis, N.F.,Baquero, D.P.,Egelman, E.H.,Krupovic, M.,Wang, F.,Aspholm, M.,Remaut, H.
Cryo-EM identifies F-ENA of Bacillus thuringiensis as a widespread family of endospore appendages across Firmicutes.
Nat Commun, 16:7652-7652, 2025

PubMed Abstract: For over 100 years, Bacillus thuringiensis (Bt) has been used as an agricultural biopesticide to control pests caused by insect species in the orders of Lepidoptera, Diptera, and Coleoptera. Under nutrient starvation, Bt cells differentiate into spores and associated toxin crystals that can adopt biofilm-like aggregates. We reveal that such Bt spore/toxin biofilms are embedded in a fibrous extrasporal matrix, and using cryoID, we resolved the structure and molecular identity of an uncharacterized type of pili, referred to here as Fibrillar ENdospore Appendages or F-ENA. F-ENA are monomolecular protein filaments anchored to the exosporium and tipped with a flexible fibrillum. Phylogenetic and structural analyses reveal that F-ENA are conserved in Bacilli and Clostridia, featuring head-neck domains with β-barrel necks that interlock via N-terminal hook peptides. In Bacillus, two collagen-like proteins (F-Anchor and F-BclA), respectively, tether F-ENA and form the distal tip. Sedimentation assays suggest F-ENA promotes spore clustering via F-BclA contacts and/or filament bundling.

PubMed: 40818982
DOI: 10.1038/s41467-025-62896-3

Experimental method

ELECTRON MICROSCOPY (4.1 Å)