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| Title | Auto-crosslinking sporesilk fibers promote endospore and Cry toxin clustering. |
|---|---|
| Journal, issue, pages | Nat Commun, Vol. 17, Issue 1, Year 2026 |
| Publish date | Mar 11, 2026 |
 Authors | Mike Sleutel / Adrià Sogues / Han Remaut /  |
| PubMed Abstract | Bacillus thuringiesis infects and kills insect larvae via its spores and associated entomotoxin-containing parasporal bodies (PSBs). We show that endospores and PSBs of B. thuringiensis Sv. ...Bacillus thuringiesis infects and kills insect larvae via its spores and associated entomotoxin-containing parasporal bodies (PSBs). We show that endospores and PSBs of B. thuringiensis Sv. Israëlensis are covered in a 'sporesilk' matrix that consist of 8 nm wide fibers with a double helical symmetry, formed by protofilaments of stacked alphahelical hairpins. These alpha endospore appendages ('A-ENA') are stabilized by up to ten autocatalytic and proximity-induced intermolecular isopeptide bonds per subunit, forming a continuous covalent polymer with remarkable chemical and physical robustness. We show A-ENA functions as B. thuringiensis virulence factor, increasing insecticidal activity by clustering spores and PSBs into an infectious clumps. Moreover, we demonstrate the recombinant production and self-assembly of A-ENA nanofibers, and show that the exogenic addition of A-ENA fibers to B. thuringiensis strains natively lacking sporesilks results in spore-PSB clustering and gain of virulence, enabling the rational, non-GMO functionalization of these biological pest control agents. |
 External links | Nat Commun / PubMed:41813682 / PubMed Central |
| Methods | EM (helical sym.) |
| Resolution | 2.1 Å |
| Structure data | EMDB-52871, PDB-9ihh: |
| Chemicals |  ChemComp-HOH: |
| Source |
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 Keywords | PROTEIN FIBRIL / endospore / isopeptide bond / A-ENA / cross-linked / protein fiber / autocatalytic |
bacillus thuringiensis serovar israelensis (bacteria)