中文摘要：

越野他汀（kosinostatin,KST）是从海洋小单孢菌Micromonospora sp.TP-A0468中分离得到的一种具有良好抗肿瘤活性的蒽环类抗生素.在对越野他汀生物合成基因簇的研究中,构建了3,5-差向异构酶基因kstD3的基因中断突变株mKOSD3,该菌株中一种新的天然产物因产量较野生型有所提高而被发现.分离新化合物并进行结构鉴定,结果显示该化合物是异醌环素B C-3＇＇位脱氧的结构类似物,命名为脱氧异醌环素B.生物活性测试表明,相比于异醌环素B,其体外细胞毒性明显降低.进一步的基因敲除实验发现,基因簇中的kstD5编码的是一个对糖基底物识别不专一的糖基转移酶,这为利用该酶的特性获得更多蒽环类衍生物奠定了基础.

英文摘要：

Kosinostatin （KST）, isolated from the fermentation extraction of Micromonospora sp. TP-A0468, is a kind of an- thraquinones antibiotic with antitumor activity. To investigate the function of kstD3 gene, encoding a sugar 3,5-epimerase involved in the KST biosynthetic gene cluster, the gene disruption mutant strain Micromonospora sp. TP-A0468 mKOSD3 is constructed. A novel compound, deoxy-isoquinocycline B was discovered and isolated from this mutant strain and its structure was characterized by comparison to the HRMS and NMR spectra of isoquinocyeline B. This compound could be considered as an analogue of isoquinocycline B. Compared with isoquinocycline B, its antitumor activity decreased significantly. It is also found that the glycosyltransferase KstD5 is more substrate-flexible than anticipated, which lay the foundation for further using the characteristics of this enzyme to obtain more analogues.