Li Mingzhu, Chen Yuan, Wang Lijuan, Lu Chujie, Chen Peiying, Jin Yuanling, Li Jiacong, Gao Fei, Shang Zhuo, Lin Wei
Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, Nanjing, China.
Department of Pathogen Biology, School of Medicine and Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, China.
Front Microbiol. 2022 Dec 12;13:1045291. doi: 10.3389/fmicb.2022.1045291. eCollection 2022.
The growing threat of antibiotic-resistant bacterial infections to public health necessitates the development of novel antibacterial agents. Inhibiting bacterial cell wall synthesis has remained a key focus for antibiotic development. Our search for inhibitors of undecaprenyl diphosphate synthase (UPPS), an essential enzyme required for bacterial cell wall formation, revealed that two primary components of gamboge, gambogic acid (GA) and neogambogic acid (NGA), significantly inhibited the activity of UPPS (UPPS) with the half maximal inhibitory concentrations (IC) of 3.08 μM and 3.07 μM, respectively. In the antibacterial assay, both GA and NGA also exhibited inhibitory activities against with the minimal inhibitory concentrations (MICs) of 2 μg/mL. Using microscale thermophoresis, molecular docking, and enzymatic assays, we further confirmed that GA and NGA occupy the substrate binding pocket of UPPS with micro-molar binding affinity, preventing the natural substrates farnesyl diphosphate (FPP) from entering. Mutagenesis analysis revealed that L91 and L146 are two key residues in the binding between GA/NGA and UPPS. Furthermore, we also demonstrated that GA and NGA can improve -induced undesirable inflammation in a mouse infection model. Taken together, our findings provide a basis for structural optimization of GA/NGA to develop improved antibiotic leads and enhance treatment success rates in clinical practice.
抗生素耐药性细菌感染对公共卫生构成的威胁日益增加，因此有必要开发新型抗菌剂。抑制细菌细胞壁合成一直是抗生素开发的关键重点。我们对细菌细胞壁形成所需的必需酶——十一异戊二烯二磷酸合酶（UPPS）的抑制剂进行了研究，结果表明，藤黄的两种主要成分——藤黄酸（GA）和新藤黄酸（NGA），能显著抑制UPPS的活性，其半数最大抑制浓度（IC）分别为3.08 μM和3.07 μM。在抗菌试验中，GA和NGA对[具体细菌]也表现出抑制活性，最低抑菌浓度（MIC）为2 μg/mL。通过微量热泳动、分子对接和酶活性测定，我们进一步证实，GA和NGA以微摩尔级的结合亲和力占据UPPS的底物结合口袋，阻止天然底物法尼基二磷酸（FPP）进入。诱变分析表明，L91和L146是GA/NGA与UPPS结合的两个关键残基。此外，我们还证明了GA和NGA可以改善小鼠感染模型中[具体因素]诱导的不良炎症。综上所述，我们的研究结果为GA/NGA的结构优化提供了依据，以开发改进的抗生素先导物，并提高临床治疗成功率。
