%0 Journal Article
%T Domain swapping of Cry1Aa and Cry1Ca from Bacillus thuringiensis influence crystal formation and toxicity<br>苏云金芽孢杆菌Cry1Aa和Cry1Ca结构域交换对晶体形态和杀虫活性影响
%A GUO Qing-yun
%A CAI Quan-xin
%A HAN Bei
%A YUAN Zhi-ming
%A <br>郭青云
%A 蔡全信
%A 韩蓓
%A 袁志明
%J 微生物学报
%D 2006
%I 
%X Bacillus thuringiensis has been successfully used for agricultural pest and medical insect control with its significant benefits based on environmental and safety considerations. However, the deficiency of this pesticide, such as limited spectrum of insecticidal activity, low toxicity to the targets and the inducement of insect resistance, results in the urgent need to exploit new resources of B. thuringiensis or to modify known strains by genetic engineering. In this study, six recombinant Bacillus thuringiensis BT-ACC, BT-AAC, BT-ACA, BT-CAA, BT-CCA and BT-CAC were constructed through the domain swapping between crystal protein Cry1Aa and Cry1Ca. SDS-PAGE and Western blot revealed that only the recombinant BT-CAA and BT-CCA produced a 135kDa chimeric protein Cry1CAA and Cry1CCA respectively, but the production level was lower than the native protein CrylAa and CrylCa. These chimeric crystal proteins could be activated by trypsin, giving a 65kDa protease-resistant core toxin as the native crystal proteins Cry1Aa and Cry1Ca. Electron microscopy study indicated that the two chimeric proteins could be produced and accumulated as spherical or granules crystals during sporulation of BT-CAA and BT-CCA, whereas native Cry1Aa and Cry1Ca were accumulated as bipyramidal crystals. Unexpectedly, the toxicity of purified chimeric crystal proteins Cry1CAA and Cry1 CCA was 3 - 5 times lower to Spodoptera exigua, and 190 - 260 times lower to Helicoverpa armigera than that of native Cry1Aa and Cry1Ca. These data suggested that the domain swapping of different crystal proteins might influence the formation and toxicity to targets of chemeric crystal proteins.
%K Bacillus thuringiensis
%K Cry1Aa
%K Cry1Ca
%K Domain swapping
%K Bioassay<br>苏云金芽孢杆菌
%K Cry1Aa
%K Cry1Ca
%K 结构域交换
%K 生物测定
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=90BA3D13E7F3BC869AC96FB3DA594E3FE34FBF7B8BC0E591&jid=A3C6BA55AB623B90FA9104CFFC826F3C&aid=45B71EB49BC48BFE&yid=37904DC365DD7266&vid=D997634CFE9B6321&iid=B31275AF3241DB2D&sid=0FCE62EC9DC00F5E&eid=58AAF01A97187A3A&journal_id=0001-6209&journal_name=微生物学报&referenced_num=0&reference_num=16