Shin Daniel, Byun Woong Sub, Moon Kyuho, Kwon Yun, Bae Munhyung, Um Soohyun, Lee Sang Kook, Oh Dong-Chan
Natural Products Research Institute, College of Pharmacy, Seoul National University, Seoul, South Korea.
Front Chem. 2018 Oct 18;6:498. doi: 10.3389/fchem.2018.00498. eCollection 2018.
Microbial culture conditions in the laboratory, which conventionally involve the cultivation of one strain in one culture vessel, are vastly different from natural microbial environments. Even though perfectly mimicking natural microbial interactions is virtually impossible, the cocultivation of multiple microbial strains is a reasonable strategy to induce the production of secondary metabolites, which enables the discovery of new bioactive natural products. Our coculture of marine and strains isolated together from an intertidal mudflat led to discover a new metabolite, dentigerumycin E (). Dentigerumycin E was determined to be a new cyclic hexapeptide incorporating three piperazic acids, -OH-Thr, -OH-Gly, β-OH-Leu, and a pyran-bearing polyketide acyl chain mainly by analysis of its NMR and MS spectroscopic data. The putative PKS-NRPS biosynthetic gene cluster for dentigerumycin E was found in the strain, providing clear evidence that this cyclic peptide is produced by the strain. The absolute configuration of dentigerumycin E was established based on the advanced Marfey's method, ROESY NMR correlations, and analysis of the amino acid sequence of the ketoreductase domain in the biosynthetic gene cluster. In biological evaluation of dentigerumycin E () and its chemical derivatives [2-,16--deoxydenteigerumycin E () and dentigerumycin methyl ester ()], only dentigerumycin E exhibited antiproliferative and antimetastatic activities against human cancer cells, indicating that -OH and carboxylic acid functional groups are essential for the biological activity.
实验室中的微生物培养条件，传统上是在一个培养容器中培养一个菌株，这与自然微生物环境有很大不同。尽管完美模拟自然微生物相互作用几乎是不可能的，但多种微生物菌株的共培养是诱导次级代谢产物产生的合理策略，这有助于发现新的具有生物活性的天然产物。我们从潮间带泥滩共同分离出的海洋菌株和菌株的共培养，导致发现了一种新的代谢产物，齿霉素E（）。通过对其核磁共振（NMR）和质谱（MS）光谱数据的分析，确定齿霉素E是一种新的环状六肽，包含三个哌嗪酸、-OH-苏氨酸、-OH-甘氨酸、β-OH-亮氨酸以及一个带有吡喃的聚酮酰基链。在菌株中发现了推测的齿霉素E的聚酮合酶-非核糖体肽合成酶（PKS-NRPS）生物合成基因簇，这清楚地证明了这种环状肽是由菌株产生的。基于先进的马尔费方法、旋转核Overhauser效应光谱（ROESY）核磁共振相关性以及对生物合成基因簇中酮还原酶结构域氨基酸序列的分析，确定了齿霉素E的绝对构型。在对齿霉素E（）及其化学衍生物[2-，16-脱氧齿霉素E（）和齿霉素甲酯（）]的生物学评价中，只有齿霉素E对人类癌细胞表现出抗增殖和抗转移活性，表明-OH和羧酸官能团对生物活性至关重要。
