摘要
非核糖体肽(NRP)是具有化学结构和生物活性多样性的一类重要的天然产物,其肽骨架的生物合成是由非核糖体肽合成酶(NRPS)催化完成。所有的NRPS含有三个最基本的催化功能域:腺苷化功能域(A domain),肽载体蛋白功能域(PCP)和缩合功能域(C domain)。在菌株优选和天然产物的探索发现中,基于天然产物生物合成中重要蛋白质的保守氨基酸序列设计简并引物而进行的PCR筛选已经成为一种十分有效的方法。在本研究中,基于NRPS中腺苷化功能域的保守序列设计简并引物,用PCR的方法从100株土壤放线菌中筛选得到了21株"阳性"菌株。在对21株"阳性"菌株的小规模发酵粗提物的HPLC分析基础上,选择了其中一株链霉菌HMU0027进行大规模发酵培养,通过色谱分离和谱学技术鉴定得到了七个NRPS产生的thiazostatin类嗜铁素(siderophore)类似物(1–7)。其中化合物1是一个新化合物,其含有罕见的苯酚类嗜铁素与糖基团连接的结构特色。本研究为进一步对这些thiazostatin类似物的生物合成研究打下了坚实基础,并展示了基于生物合成知识的基因组挖掘技术在非核糖体肽类天然产物探索发现中的巨大潜力。
Nonribosomal peptides (NRPs) represent a large family of natural products with great diversities of chemical structures and biological activities. The peptide backbones of NRPs are synthesized by nonribosomal peptide synthetases (NRPSs) that minimally consist of one adenylation (A) domain, one peptidyl carrier protein (PCP) and one condensation (C) domain. In this study, we carded out a PCR screening and identified 21 "positive" strains from 100 actinomycete strains with the degenerate primers designed from the conserved sequences of A domains of NRPSs. One of the 21 "positive" strains, Streptomyces sp. HMU0027, was selected for large-scale fermentation (9 L) based on HPLC analysis, and subsequent isolation and structural elucidation afforded seven NRPS-synthesized thiazostatin siderophore analogues (1-7). Compound 1 was a new compound containing an unusual linkage between a phenolate siderophore and a sugar moiety. These results laid the foundation for further biosynthetic research of these thiazostatin analogues and highlighted the power of genome mining technologies based on biosynthetic knowledge in NRP discovery.
基金
The National Natural Science Foundation of China(Grant No.81573326,Grant No.81673332)