Cyt1Aa, one of four crystalline protoxins produced by mosquitocidal bacterium Bacillus thuringiensis israelensis (Bti), forms oligomers that fully perforate and eventually disrupt lipid bilayers. About 35 min after toxin addition, membrane perforation is observed at the periphery of membrane-bound aggregates. The depth of holes can reach 4.5 nm, consistent with a full spanning of the lipid bilayer.
AFM imaging of Cyt1Aa crystals, provided by Guillaume Tetreau, as well as the interaction between Cyt1Aa and lipid bilayers were performed by Jean-Marie Teulon.
Tetreau G, et al. (2020) Serial femtosecond crystallography drives elucidation of mosquitocidal Cyt1Aa bioactivation cascade, from in vivo crystallization to cell lysis. Nat. Comm. 11 : 1153.