The protoxin composition of Bacillus thuringiensis insecticidal inclusions affects solubility and toxicity
The protoxin composition of Bacillus thuringiensis insecticidal inclusions affects solubility and toxicity
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DOI：
10.1128/aem.61.11.4057-4060.1995
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发表时间：
1995-11
影响因子：
4.4
通讯作者：
A. Aronson
中科院分区：
文献类型：
--
作者：
A. Aronson
大多数产生对鳞翅目有活性的毒素的苏云金芽孢杆菌菌株含有几个质粒编码的δ-内毒素基因，并将相关的原毒素包装成单个包含物。以前发现，在B.苏云金aizawai HD 133，其产生包含CryIAb、CryIC和CryID原毒素的内含物，在约1%的细胞中含有cryIAb基因的45-mDa质粒自发丢失。结果，由固化菌株产生的内含物在pH 9.2或9.5下不太容易溶解，并且对Plodia interpunctella的毒性降低，尽管存在CryIC原毒素，其在溶解时是活性的。这些结果表明，原毒素组合物是一个因素，在包容溶解度和毒性和cryIAb基因，这也是目前在一个不稳定的质粒在其他几个亚种，可能有一个独特的作用，包容溶解度和毒性。将该基因的克隆拷贝导入B的质粒固化衍生物中。苏云金aizawai HD 133导致所有包涵体蛋白在pH9.2下的溶解度从小于20%增加到大于45%，并且使草地贪夜蛾的包涵体的50%致死浓度（LC 50，以微克[干重]每平方厘米计）从35降低到10。这些值与从B中发现的夹杂物相同。苏云金aizawai HD 133，并且在所有情况下，溶解的原毒素的LC 50为10。含有相关cryIA基因的转化体产生的内含物在pH 9.2下溶解超过95%，但LC 50也为10。（250字处删节）
Most Bacillus thuringiensis strains producing toxins active on lepidoptera contain several plasmid-encoded delta-endotoxin genes and package related protoxins into a single inclusion. It was previously found that in B. thuringiensis subsp. aizawai HD133, which produces an inclusion comprising the CryIAb, CryIC, and CryID protoxins, there is a spontaneous loss in about 1% of the cells of a 45-mDa plasmid containing the cryIAb gene. As a result, inclusions produced by the cured strain were less readily solubilized at pH 9.2 or 9.5 and had a decreased toxicity for Plodia interpunctella, despite the presence of the CryIC protoxin, which was active when solubilized. These results suggested that protoxin composition was a factor in inclusion solubility and toxicity and that the cryIAb gene, which is also present on an unstable plasmid in several other subspecies, may have a unique role in inclusion solubility and toxicity. Introduction of a cloned copy of this gene into the plasmid-cured derivative of B. thuringiensis subsp. aizawai HD133 resulted in an increase in the solubility at pH 9.2 of all of the inclusion proteins from less than 20% to greater than 45% and a lowering of the 50% lethal concentration (LC50, in micrograms [dry weight] per square centimeter) of inclusions for Spodoptera frugiperda from 35 to 10. These values are the same as those found with inclusions from B. thuringiensis subsp. aizawai HD133, and in all cases, the LC50 of the solubilized protoxins was 10. Transformants containing related cryIA genes produced inclusions which were more than 95% solubilized at pH 9.2 but also had LC50 of 10.(ABSTRACT TRUNCATED AT 250 WORDS)