View source for Insecticidal delta-endotoxin Cyt2Ba from Bacillus thuringiensis

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The Cyt family of proteins consists of -endotoxins expressed during sporulation of several subspecies of ''Bacillus thuringiensis''. Its members possess insecticidal, hemolytic and cytolytic activities through pore formation, and attract attention due to their potential use as vehicles for targeted membrane-destruction. The -endotoxin of subsp. ''israelensis'' includes three Cyt species, a major Cyt1Aa and two minor proteins Cyt2Ba and Cyt1Ca. Cleaved Cyt protein that lacks the N- and C-terminal segments form toxic monomers. Here, we describe the crystal structure of Cyt2Ba, cleaved at its amino and carboxy terminus by bacterial endogenous protease(s). Overall, its fold resembles that of the previously described <scene name='Image:Cyt2Ba.pdb/Volvatoxin_a2/1'>Volvatoxin A2 (VVA2)</scene> and the non-toxic form of <scene name='Cyt2Ba/Alignment_cyt2a/1'>Cyt2A</scene>. The structural similarity between these three proteins may provide information regarding the mechanism(s) of membrane perforating toxins.




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