天然产物萨茹菌素的发现及其生物合成研究

	天然产物萨茹菌素的发现及其生物合成研究; Study on the discovery and biosynthesis of sarubicins
	喻明明
导师	黄胜雄
摘要	Secondary metabolites from microorganisms, especially from the genus Streptomyces, are an important source of bioactive natural products. Among various microbial metabolites, glycosylated natural products (GNPs) receive much attentions by researchers due to their structural diversities and biological properties. Commonly, glycosylation in the biosynthesis of natural products is catalyzed by glycosyltransferase, forming one glycosidic bond to the C-1 position of the sugar part. But in few cases, like rubrolone and granaticin A, the sugar parts are connected to the aglycones with an additional C-C linkage at the C-2 or C-4 position. In recent years, with the development of genomic sequencing technology and the in-depth studying on NPs biosynthesis, genome mining has become a popular strategy for guiding the discovery of novel natural products. In the second chapter, we scanned the genome of the actinomycetes collection in our lab using the glycosylation-related genes in granaticin A biosynthesis as probes, leading the identification of four putative C-glycosylated NPs producers. Subsequent large-scale fermentation and isolation resulted in the isolation of sarubicin A (1) and B (2), along with six new natural products 4 and 9-13), from one of the candidate strains Streptomyces sp. KIB-H91. The metabolites of other three strains were also investigated and led to the isolation of a new streptazone analog (25) and a vinyl indole derivate (37). Sarubicin A possesses an atypical sugar moiety which is the same as that of granaticin A and a quinone aglycone derived from shikimic acid. To explore the embedded biosynthesis mechanism, we chose sarubicin A as our study object. In the third chapter, molecular biological techniques were used to construct heterologous expression strains housing the putative sarubicin BGC (sar BGC) and the gene cluster′s boundary were determined by gene deletion experiments. Next, in the fourth chapter, we studied the secondary metabolites of the engineered heterologous expression strain S. coelicolor M1154/p18F3 and eight different gene knockout mutant strains by fermentation, extraction, and isolation. Sarubicins A (1), B (2) and 15 related natural products were isolated from the heterologous expression strains, including three new C-glycosylated quinazolinone derivatives (45-47) and one benzoxazine analog (48). The sar BGC was suggested to be responsible for the production of the glycosylated quinazolinones. The single C-glycosidic bond between the deoxysugar and aglycone indicates the stepwise formation mechanism of the two unusual C-C bonds in sarubicins biosynthesis. In addition, 32 compounds were isolated from the fermentation broth of gene-knockout mutant strains, of which 68 and 69 were two new natural quinazolinones. Meanwhile, we chemically synthesized two aglycone- related intermediates 6-hydroxyanthranilamide and 5,8-dihydroxy-2-methyl-4(3H)- quinazolinone for feeding study. The origin of the aglycone of 1 could
	2021-05
文献类型	学位论文
条目标识符	http://ir.kib.ac.cn/handle/151853/74594
专题	昆明植物所硕博研究生毕业学位论文
推荐引用方式 GB/T 7714	喻明明. 天然产物萨茹菌素的发现及其生物合成研究, Study on the discovery and biosynthesis of sarubicins[D],2021.

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