Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250103, Shandong Province, China.
State Key Laboratory of Bioreactor Engineering, and School of Biotechnology, East China University of Science and Technology (ECUST), Shanghai, 200237, China.
Appl Microbiol Biotechnol. 2022 Apr;106(8):3093-3102. doi: 10.1007/s00253-022-11925-y. Epub 2022 Apr 26.
Chaetomium fungi produce a diversity of bioactive compounds. Chaetomium cochliodes SD-280 possesses 91 secondary metabolite gene clusters and exhibits strong antibacterial activity. One of the active compounds responsible for that activity, chetomin, has a minimum inhibitory concentration (MIC) for anti-methicillin-resistant Staphylococcus aureus (MRSA) of 0.05 μg/mL (vancomycin: 0.625 μg/mL). This study demonstrated that the addition of glutathione (GSH) can enhance chetomin yield dramatically, increasing its production 15.43-fold. Following genome sequencing, cluster prediction, and transcriptome and proteome analyses of the fungus were carried out. Furthermore, a relatively complete chetomin biosynthetic gene cluster was proposed, and the coding sequences were acquired. In the cluster of GSH-treated cells, proteome analysis revealed two up-regulated proteins that are critical enzymes for chetomin biosynthesis. One of these enzymes, a nonribosomal peptide synthetase (NRPS), was heterologously expressed in Aspergillus nidulans, and one of its metabolites was determined to be an intermediate in the chetomin biosynthetic pathway. We present here, to our knowledge, the first experimental evidence that chetomin exhibits strong bioactivity against MRSA. Our work also provides extensive insights into the biosynthetic pathway of chetomin, in particular identifying two key enzymes (glutathione S-transferase (CheG) and NRPS (CheP)) that substantially up-regulate chetomin. These mechanistic insights into chetomin biosynthesis will provide the foundation for further investigation into the anti-pathogenic properties and applications of chetomin. KEY POINTS: • Chetomin exhibits strong anti-MRSA activity with MIC of 0.05 μg/mL. • Addition of glutathione improved the yield of chetomin by 15.43-fold. • CheG and CheP involved in the chetomin biosynthesis were revealed for the first time.
毛壳菌属真菌产生多种生物活性化合物。Chaetomium cochliodes SD-280 拥有 91 个次生代谢产物基因簇，表现出很强的抗菌活性。其中一种具有抗耐甲氧西林金黄色葡萄球菌 (MRSA) 活性的活性化合物，chetomin，对 MRSA 的最低抑菌浓度 (MIC) 为 0.05μg/mL（万古霉素：0.625μg/mL）。本研究表明，添加谷胱甘肽 (GSH) 可以显著提高 chetomin 的产量，使其产量增加 15.43 倍。对真菌进行基因组测序、簇预测以及转录组和蛋白质组分析后。此外，提出了一个相对完整的 chetomin 生物合成基因簇，并获得了其编码序列。在 GSH 处理的细胞簇中，蛋白质组分析揭示了两个上调的蛋白，它们是 chetomin 生物合成的关键酶。其中一种酶是非核糖体肽合成酶 (NRPS)，在构巢曲霉中异源表达，其一种代谢产物被确定为 chetomin 生物合成途径的中间产物。在这里，我们首次提供了实验证据，表明 chetomin 对 MRSA 具有很强的生物活性。我们的工作还为 chetomin 的生物合成途径提供了广泛的见解，特别是鉴定了两个关键酶（谷胱甘肽 S-转移酶 (CheG) 和 NRPS (CheP))，它们显著上调了 chetomin。这些对 chetomin 生物合成的机制见解将为进一步研究 chetomin 的抗病原特性和应用提供基础。 要点： • chetomin 对 MRSA 的 MIC 为 0.05μg/mL，具有很强的抗 MRSA 活性。 • 添加谷胱甘肽使 chetomin 的产量提高了 15.43 倍。 • 首次揭示了参与 chetomin 生物合成的 CheG 和 CheP。
