Abstract：
Bacterial diseases caused substantial yield losses worldwide, with the rise of antibiotic resistance, there is a critical need for alternative antibacterial compounds. Natural products (NPs) from microorganisms have emerged as promising candidates due to their potential as cost-effective and environmentally friendly bactericides. However, the precise mechanisms underlying the antibacterial activity of many NPs, including Guvermectin (GV), remain poorly understood. Here, we sought to explore how GV interacts with Guanosine 5\'-monophosphate synthetase (GMPs), an enzyme crucial in bacterial guanine synthesis. We employed a combination of biochemical and genetic approaches, enzyme activity assays, site-directed mutagenesis, bio-layer interferometry, and molecular docking assays to assess GV\'s antibacterial activity and its mechanism targeting GMPs. The results showed that GV effectively inhibits GMPs, disrupting bacterial guanine synthesis. This was confirmed through drug-resistant assays and direct enzyme inhibition studies. Bio-layer interferometry assays demonstrated specific binding of GV to GMPs, with dependency on Xanthosine 5\'-monophosphate. Site-directed mutagenesis identified key residues crucial for the GV-GMP interaction. This study elucidates the antibacterial mechanism of GV, highlighting its potential as a biocontrol agent in agriculture. These findings contribute to the development of novel antibacterial agents and underscore the importance of exploring natural products for agricultural disease management.
摘要：
细菌性疾病在全球范围内造成了巨大的产量损失，随着抗生素耐药性的上升，有一个关键的需要替代抗菌化合物。来自微生物的天然产物（NP）由于其作为具有成本效益和环境友好的杀菌剂的潜力而成为有前途的候选物。然而,许多NPs抗菌活性的精确机制，包括古维菌素（GV），仍然知之甚少。这里,我们试图探索GV如何与鸟苷5'-单磷酸合成酶（GMPs）相互作用，一种在细菌鸟嘌呤合成中至关重要的酶。我们采用了生化和遗传相结合的方法，酶活性测定，定点诱变，生物层干涉术，和分子对接试验评估GV的抗菌活性及其靶向GMPs的机制。结果表明GV能有效抑制GMPs,破坏细菌鸟嘌呤合成。这通过耐药性测定和直接酶抑制研究得到证实。生物层干涉测定法证明了GV与GMPs的特异性结合，依赖5'-单磷酸黄苷。定点诱变鉴定了对GV-GMP相互作用至关重要的关键残基。本研究阐明了GV的抗菌机制,强调其作为农业生物防治剂的潜力。这些发现有助于新型抗菌剂的开发，并强调了探索天然产物对农业疾病管理的重要性。
