恰塔努加链霉菌多重次级代谢过程调控机制的探索
发布时间：2019-02-16 16:18
【摘要】：链霉菌是活性天然产物的重要来源。研究表明,工业链霉菌基因组中除目标产物外,往往含有丰富的隐性次级代谢基因簇。如何激活这些基因簇,是充分挖掘链霉菌药用基因资源的关键。链霉菌次级代谢产物的生物合成过程由复杂的多层次调控系统所控制,其中γ-丁酮内酯(GBL)信号系统就是其中一个重要的调控体系。本论文针对纳他霉素工业生产菌恰塔努加链霉菌L10进行研究,揭示了恰塔努加链霉菌GBL分子受体协同调控机制；同时解析了恰塔努加链霉菌隐性角蒽酮类化合物基因簇激活的分子机制。早期研究表明L10中GBL受体ScgR与GBL合成酶ScgA组成一个全局调控体系。通过基因芯片比较△scgA和L10在转录组上的差别,我们发现ScgA参与糖酵解、三羧酸循环等初级代谢过程；同时,多种调控蛋白和次级代谢基因簇在△scgA中的转录水平也有明显变化。SprA是ScgR的重要同源蛋白,△sprA表现为固体培养基上形态分化滞后及液体培养基中纳他霉素产量下降；EMSA和DNase Ⅰ footprinting实验表明,SprA可以结合自身基因上游两个自调控元件,意味着SprA具有自我调控作用。基因芯片数据表明sprA的转录受到ScgA的正调控作用；然而SprA通过抑制ScgA的转录从而参与调控GBL信号分子的产生。大肠杆菌异源荧光检测表明SprA可以直接调控scgR的转录。因此,SprA是一个通过影响GBL信号分子产生,从而参与形态分化和次级代谢的全局调控蛋白。基因组测序表明恰塔努加链霉菌L10中存在34个次级代谢基因簇(包括目标产物纳他霉素),然而大部分基因簇在实验室条件下以沉默状态存在。通过生物信息学分析,发现其中含有一个隐性的角蒽酮类化合物基因簇(命名为恰塔霉素基因簇)。通过在L10中过表达途径特异性调控基因chal,成功激活了恰塔霉素基因簇并检测到恰塔霉素A和B。结构解析表明恰塔霉素A和恰塔霉素B属于结构新颖的角蒽酮类化合物。细胞活性实验表明恰塔霉素B具有较好的抗肿瘤细胞增殖活性和抗细菌活性。研究表明,GBL信号受体ScgR、SprA及GBL信号合成酶ScgA协同参与调控恰塔霉素的产生。本研究内容揭示了一种快速激活角蒽酮类化合物的策略。
[Abstract]:Streptomyces is an important source of active natural products. Studies have shown that the genome of Streptomyces industrial is rich in recessive secondary metabolic gene clusters in addition to its target products. How to activate these gene clusters is the key to fully tap the medicinal gene resources of Streptomyces. The biosynthesis of secondary metabolites of Streptomyces is controlled by a complex multi-level regulatory system in which 纬 -butanone lactone (GBL) signaling system is one of the important regulatory systems. In this paper, the co-regulation mechanism of GBL receptor of Streptomyces chattanoogas L10 was studied. At the same time, the molecular mechanism of gene cluster activation of recessive keratoanthrone compounds in Streptomyces chattanoogas was analyzed. Early studies showed that GBL receptor ScgR and GBL synthase ScgA constituted a global regulatory system in L 10. By comparing the transcriptional differences between scgA and L10, we found that ScgA is involved in glycolysis, tricarboxylic acid cycle and other primary metabolic processes. At the same time, the transcriptional level of many regulatory proteins and secondary metabolic gene clusters in scgA also changed obviously. SprA is an important homologous protein of ScgR, and sprA is characterized by delayed morphological differentiation on solid medium and decrease of natamycin production in liquid medium. EMSA and DNase 鈪，
本文编号：2424623
[Abstract]:Streptomyces is an important source of active natural products. Studies have shown that the genome of Streptomyces industrial is rich in recessive secondary metabolic gene clusters in addition to its target products. How to activate these gene clusters is the key to fully tap the medicinal gene resources of Streptomyces. The biosynthesis of secondary metabolites of Streptomyces is controlled by a complex multi-level regulatory system in which 纬 -butanone lactone (GBL) signaling system is one of the important regulatory systems. In this paper, the co-regulation mechanism of GBL receptor of Streptomyces chattanoogas L10 was studied. At the same time, the molecular mechanism of gene cluster activation of recessive keratoanthrone compounds in Streptomyces chattanoogas was analyzed. Early studies showed that GBL receptor ScgR and GBL synthase ScgA constituted a global regulatory system in L 10. By comparing the transcriptional differences between scgA and L10, we found that ScgA is involved in glycolysis, tricarboxylic acid cycle and other primary metabolic processes. At the same time, the transcriptional level of many regulatory proteins and secondary metabolic gene clusters in scgA also changed obviously. SprA is an important homologous protein of ScgR, and sprA is characterized by delayed morphological differentiation on solid medium and decrease of natamycin production in liquid medium. EMSA and DNase 鈪，
本文编号：2424623
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