苏云金芽胞杆菌杀虫增效天然产物Zwittermicin A生物合成中的重要调控因子及其作用方式

Bacillus thuringiensis (Bt) is currently one of the most successful development microbial insecticides. Zwittermicin A (ZmA) is an aminopolyol antibiotic discovered from Bt. It displays broad-spectrum antimicrobial activity and synergistically activity with the crystal proteins from Bt. ZmA is a necessary active ingredient of highly active Bt preparations, and its yield directly determines the quality of Bt preparations. The biosynthetic pathway and resistance mechanism of ZmA have been revealed, but the regulatory mechanism of ZmA biosynthesis is still unknown. According to our early research findings, three negative regulatory factors, which can obviously effect the ZmA production, were found: ORF123, a transcriptional regulator with low similarity to any known regulator; ZmaS, a 4'-phosphopantetheinyl transferase which has been reported could act as a regulator recently, but its regulatory mechanism is still unknown; ZmaC, a structural protein which responsible for the additional metabolite B. In this study, we aim to reveal their regulatory mechanism, and screen other important regulators which can obviously effect the ZmA production from the Bt transposon insertion mutant library. In further, we intend to discuss the interaction of these important regulators and their respective regulatory pathways, while the regulatory network of ZmA biosynthesis will be present preliminarily, which give the theoretical basis for the construction of genetic engineering Bt strain with high-producing ZmA and promoting the application of Bt preparations.

苏云金芽胞杆菌(Bt)是目前世界上开发最成功的杀虫微生物之一。Zwittermicin A(ZmA)是Bt中发现的氨基多元醇类抗生素；除抑菌谱广外，其对Bt杀虫晶体蛋白还有显著杀虫增效作用，是高效Bt制剂的必需活性成份，其产量直接决定了Bt制剂的质量。ZmA生物合成途径和抗性机理已揭示，但调控机制未知。申请人前期发现了三个明显影响ZmA生物合成的负调控因子：结构上新型的转录调控因子ORF123、近年来报道新发现兼具有合成调控作用但机制未明的磷酸泛酰巯基乙胺基转移酶ZmaS、参与ZmA副产物生物合成的ZmaC。本申请项目拟重点研究它们对ZmA生物合成的调控方式，并继续利用Bt转座子随机插入突变体库发掘其它明显影响ZmA生物合成的重要调控因子，研究这些重要调控因子所在的调控通路有无相互影响，初步建立ZmA生物合成的调控网络。本研究将为高产ZmA的Bt菌株的构建、推进Bt制剂的应用奠定理论基础。

苏云金芽胞杆菌(Bt)是目前世界上开发最成功的杀虫微生物之一。Zwittermicin A(ZmA)是Bt中发现的氨基多元醇类抗生素；除抑菌谱广外，其对Bt杀虫晶体蛋白还有显著杀虫增效作用，是高效Bt制剂的必需活性成份，其产量直接决定了Bt制剂的质量。本项目在申请人前期发现的几个明显影响ZmA生物合成的调控因子基础上，从几个方面对ZmA生物合成的调控机制进行了阐述：①确定了本身作为磷酸泛酰巯基乙胺基转移酶，新发现可以参与合成调控的ZmaS的调控方式，表明ZmaS与ZmA的生物合成直接相关，且负调控了紧邻ZmA合成基因簇下游、同样具有重要生物活性的kanosamine的生物合成；②通过ZmaB-Te融合重组子的构建，解析了结构蛋白ZmaB对ZmA生物合成的调控途径，表明Te域释放ZmA前体物的效率显著大于ZmaL；③阐明了ZmaM对ZmA生物合成的作用，表明ZmA的生物合成途径复杂，在菌株中存在ZmA肽酶修饰和转运的互补途径；④拓展了ZmA在健康水产养殖中的应用潜力，研究表明ZmA对水产致病菌的生长具有良好的抑制作用，产ZmA的芽胞杆菌与水产致病菌的拮抗作用提高了ZmA合成相关基因的表达，提示我们从菌株互作的角度，发掘新的提高ZmA产量的调控途径。研究结果为高产ZmA的Bt菌株的构建、推进Bt制剂的应用奠定了理论基础。