Bacillus thuringiensis crystal 6Aa (Cry6Aa) toxin, and similar proteins
This model includes pesticidal Cry6Aa toxin from Bacillus thuringiensis, one of the many parasporal crystal (Cry) toxins produced during the sporulation phase of growth. Many of these proteins are toxic to numerous insect species and have been effectively used as proteinaceous insecticides to directly kill insect pests; some have been used to control insect growth on transgenic agricultural plants. Cry6Aa exists as a protoxin, which is activated by cleavage using trypsin. Structure studies for Cry6Aa support a mechanism of action by pore formation, similar to cytolysin A (ClyA)-type alpha pore-forming toxins (alpha-PFTs) such as HblB, and bioassay and mutation studies show that Cry6Aa is an active pore-forming toxin. Cry6Aa shows atypical features compared to other members of alpha-PFTs, including internal repeat sequences and small loop regions within major alpha helices.
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