摘要
<i><span style="font-family:Verdana;">Bacillus thuringiensis</span></i><span style="font-family:""><span style="font-family:Verdana;"> (Bt) produces two families of insecticidal crystal proteins, </span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;">, crystalline (Cry) and cytolytic (Cyt) toxins. Cyt3Aa1, the newest Cyt family member, is produced by Bt TD516. Bioassay results have shown that Cyt3Aa1 has weak hemolytic activity against human red blood cells and is not toxic to </span><i><span style="font-family:Verdana;">A.</span></i></span><i><span style="font-family:""> </span></i><i><span style="font-family:Verdana;">aegypti</span></i><span style="font-family:Verdana;"> larvae, but causing a teratogenic effect. The three-dimensional structure of Cyt3Aa1 ha</span><span style="font-family:Verdana;">s </span><span style="font-family:""><span style="font-family:Verdana;">a typical cytolysin fold containing a </span><i><span style="font-family:Verdana;">β</span></i><span style="font-family:Verdana;">-sheet held by two surrounding </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-helical layers, resembling the previously reported Cyt1Aa and Cyt2Aa structures, which indicated that Cyt3Aa1 might be a membrane-perforation toxin and could induce synergism with Cry protein. This study provides a new source of insecticidal crystal proteins, and presents a foundation for understanding the biological characterization of it, which will aid in the development of strategies to cope with the potential problem of insect resistance.
<i><span style="font-family:Verdana;">Bacillus thuringiensis</span></i><span style="font-family:""><span style="font-family:Verdana;"> (Bt) produces two families of insecticidal crystal proteins, </span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;">, crystalline (Cry) and cytolytic (Cyt) toxins. Cyt3Aa1, the newest Cyt family member, is produced by Bt TD516. Bioassay results have shown that Cyt3Aa1 has weak hemolytic activity against human red blood cells and is not toxic to </span><i><span style="font-family:Verdana;">A.</span></i></span><i><span style="font-family:""> </span></i><i><span style="font-family:Verdana;">aegypti</span></i><span style="font-family:Verdana;"> larvae, but causing a teratogenic effect. The three-dimensional structure of Cyt3Aa1 ha</span><span style="font-family:Verdana;">s </span><span style="font-family:""><span style="font-family:Verdana;">a typical cytolysin fold containing a </span><i><span style="font-family:Verdana;">β</span></i><span style="font-family:Verdana;">-sheet held by two surrounding </span><i><span style="font-family:Verdana;">α</span></i><span style="font-family:Verdana;">-helical layers, resembling the previously reported Cyt1Aa and Cyt2Aa structures, which indicated that Cyt3Aa1 might be a membrane-perforation toxin and could induce synergism with Cry protein. This study provides a new source of insecticidal crystal proteins, and presents a foundation for understanding the biological characterization of it, which will aid in the development of strategies to cope with the potential problem of insect resistance.
