Development and optimization of an intergeneric conjugation system and analysis of promoter activity in Streptomyces rimosus M527

龟裂链霉菌M527接合转移体系的建立和优化以及启动子的活性分析（英文）

An efficient genetic transformation system and suitable promoters are essential prerequisites for gene expression studies and genetic engineering in streptomycetes.In this study,firstly,a genetic transformation system based on intergeneric conjugation was developed in Streptomyces rimosus M527,a bacterial strain which exhibits strong antagonistic activity against a broad range of plant-pathogenic fungi.Some experimental parameters involved in this procedure were optimized,including the conjugative media,ratio of donor to recipient,heat shock temperature,and incubation time of mixed culture.Under the optimal conditions,a maximal conjugation frequency of 3.05^10-5 per recipie nt was obtai ned.Subseque ntly,based on the above developed and optimized tran sformati on system,the synthetic promoters SPL-21 and SPL-57,a native promoter potrB,and a constitutive promoter permE commonly used for gene expression in streptomycetes were selected and their activity was analyzed using gusA as a reporter gene in S.rimosus M527.Among the four tested promoters,SPL-21 exhibited the strongest expression activity and gave rise to a 2.2-fold increase in p-glucuronidase(GUS)activity compared with the control promoter permE.Promoter SPL-57 showed activity comparable to that of permE.Promoter potrB,which showed the lowest activity,showed a 50%decrease in GUS activity compared with the control permE.The transformation system developed in this study and the tested promotors provide a basis for the further modification of S.rimosus M527.

目的:建立并优化适用于龟裂链霉菌(Streptomyces rimosus)M527的属间接合转移体系,并在此基础上分析四个启动子的表达活性。创新点:有效的遗传转化系统和合适的启动子是链霉菌基因表达和基因工程的必要前提。由于链霉菌的遗传背景复杂,接合转移实验参数对菌种具有高度特异性。因此,本研究建立并优化了一套适用于S.rimosus M527的属间接合转移体系,并在此基础上分析比较了四个启动子的表达活性。这将为进一步遗传修饰S.rimosus M527奠定基础。方法:以S.rimosus M527为研究对象,通过对接合转移体系中的一些重要的实验参数(如接合转移培养基、供受体比例、热激温度和混合培养时长等)进行了优化。在此基础上,构建以为报告基因的质粒,通过直观显色反应以及GUS酶活的定量检测,分析比较了四个启动子的表达活性。结论:建立了一种有效的适用于S.rimosus M527接合转移体系,优化后的接合效率最高达3.05x10^-5。分析测试的四个启动子中,合成启动子SPL-21表现出最高表达活性,比常用强组成型启动子permE^*活性高出2.2倍,合成启动子SPL-57与permE^*的活性无显著差异,内源启动子permB的活性比permE^*降低了50%。