Faculty of Health Sciences, University of Johannesburg, P.O. Box 17011, Doornfontein, 2028, South Africa.
Department of Biochemistry, Faculty of Science, Stellenbosch University, Private Bag X1, Stellenbosch, 7602, South Africa.
Sci Rep. 2023 Feb 9;13(1):2360. doi: 10.1038/s41598-023-28502-6.
Secondary metabolic profiling, using UPLC-MS and molecular networking, revealed the secondary metabolites produced by Serratia marcescens NP10. The NP10 strain co-produced cyclic and open-ring stephensiolides (i.e., fatty acyl chain linked to Thr-Ser-Ser-Ile/Leu-Ile/Leu/Val) and glucosamine derivatives (i.e., fatty acyl chain linked to Val-glucose-butyric/oxo-hexanoic acid), with the structures of sixteen new stephensiolides (L-Y) and three new glucosamine derivatives (L-N) proposed. Genome mining identified sphA (stephensiolides) and gcd (glucosamine derivatives) gene clusters within Serratia genomes available on NBCI using antiSMASH, revealing specificity scores of the adenylation-domains within each module that corroborates MS data. Of the nine RP-HPLC fractions, two stephensiolides and two glucosamine derivatives exhibited activity against Staphylococcus aureus (IC of 25-79 µg/mL). H NMR analysis confirmed the structure of the four active compounds as stephensiolide K, a novel analogue stephensiolide U, and glucosamine derivatives A and C. Stephensiolides K and U were found to cause membrane depolarisation and affect the membrane permeability of S. aureus, while glucosamine derivatives A and C primarily caused membrane depolarisation. New members of the stephensiolide and glucosamine derivative families were thus identified, and results obtained shed light on their antibacterial properties and mode of membrane activity.
采用 UPLC-MS 和分子网络技术对次级代谢产物进行了分析，揭示了沙雷氏菌 NP10 产生的次级代谢产物。NP10 菌株共产生环型和开环型斯蒂芬氏内酯（即脂肪酰链连接到 Thr-Ser-Ser-Ile/Leu-Ile/Leu/Val）和氨基葡萄糖衍生物（即脂肪酰链连接到 Val-葡萄糖-丁酸/氧代-己酸），提出了十六种新的斯蒂芬氏内酯（L-Y）和三种新的氨基葡萄糖衍生物（L-N）的结构。利用 antiSMASH 在 NBCI 上对现有的沙雷氏菌基因组进行基因组挖掘，识别出 sphA（斯蒂芬氏内酯）和 gcd（氨基葡萄糖衍生物）基因簇，每个模块中的腺苷酸结构域的特异性评分与 MS 数据相符。在 9 个反相高效液相色谱（RP-HPLC）馏分中，两种斯蒂芬氏内酯和两种氨基葡萄糖衍生物对金黄色葡萄球菌（IC 为 25-79μg/mL）表现出活性。1H NMR 分析证实了四种活性化合物的结构为斯蒂芬氏内酯 K、一种新型类似物斯蒂芬氏内酯 U 以及氨基葡萄糖衍生物 A 和 C。发现斯蒂芬氏内酯 K 和 U 导致膜去极化并影响金黄色葡萄球菌的膜通透性，而氨基葡萄糖衍生物 A 和 C 主要导致膜去极化。因此，鉴定出了斯蒂芬氏内酯和氨基葡萄糖衍生物家族的新成员，研究结果揭示了它们的抗菌特性和膜活性模式。
