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Endospore appendages The surface of Bacillus and Clostridium endospores is decorated with long filamentous endospores appendages that resemble pili from Gram- negative and Gram-positive bacteria. They show two morphologies, the main or Staggered-type (S-Ena) which accounts for 90% of the fibres, and the Ladder-like (L-Ena) which is smaller and less abundant. They are a novel class of Gram-positive pili, consisting in single domain subunits with a jellyroll topology comprised by two juxtaposed beta-sheets. This domain represents the S-Ena core. Disulfide bonding through the N-terminal connector peptide that precedes this domain stabilizes longitudinally the fibres, bridging the helical turns. This results in flexible pili, highly resistant to environmental harsh such as heat, drought, and chemical damage. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",