Dong Jing, Zhang Yuze, Yang Qiuhong, Liu Yongtao, Zhou Shun, Ai Xiaohui
Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China.
College of Food Science and Engineering, Bohai University, Jinzhou 121010, China.
Animals (Basel). 2024 Apr 29;14(9):1337. doi: 10.3390/ani14091337.
Sortase A (SrtA) is responsible for anchoring surface proteins to the cell wall, and has been identified as a promising target developing anti-infective drugs of Gram-positive bacteria. The aim of the study was to identify inhibitors of () SrtA from natural compounds to overcome the spread of antibiotic resistance in aquaculture. Here, we found that the MIC of fraxetin against was higher than 256 μg/mL, indicating that fraxetin had no anti- activity. But fraxetin could dose-dependently decrease the activity of SrtA at concentrations ranging between 4-32 μg/mL by a fluorescence resonance energy transfer (FRET) assay. Moreover, the inhibition of SrtA by fraxetin decreased the anchoring of surface proteins with the LPXTG motif to the cell wall by detecting the immunofluorescence change of serine-rich repeat protein 1 (Srr1) on the bacterial cell surface. The results of fibronectin binding and cell adhesion assays indicated that fraxetin could significantly decrease the adhesion ability of in a dose-dependent manner. The results were further proven by immunofluorescence staining. Animal challenge results showed that treatment with fraxetin could reduce the mortality of tilapia infected with to 46.67%, indicating that fraxetin could provide a significant amount of protection to tilapia by inactivating SrtA. Taken together, these findings provided a novel inhibitor of SrtA and a promising candidate for treating infections in aquaculture.
分选酶A（SrtA）负责将表面蛋白锚定到细胞壁上，并且已被确定为开发抗革兰氏阳性菌感染药物的一个有前景的靶点。本研究的目的是从天然化合物中鉴定出（）SrtA的抑制剂，以克服水产养殖中抗生素耐药性的传播。在此，我们发现白蜡树素对（）的最低抑菌浓度高于256μg/mL，这表明白蜡树素没有抗（）活性。但是通过荧光共振能量转移（FRET）测定，白蜡树素在4 - 32μg/mL的浓度范围内可剂量依赖性地降低SrtA的活性。此外，通过检测细菌细胞表面富含丝氨酸的重复蛋白1（Srr1）的免疫荧光变化，发现白蜡树素对SrtA的抑制作用降低了具有LPXTG基序的表面蛋白与细胞壁的锚定。纤连蛋白结合和细胞黏附试验结果表明，白蜡树素能够以剂量依赖性方式显著降低（）的黏附能力。免疫荧光染色进一步证实了该结果。动物攻毒结果显示，用白蜡树素处理可将感染（）的罗非鱼死亡率降低至46.67%，这表明白蜡树素可通过使SrtA失活为罗非鱼提供显著的保护作用。综上所述，这些发现提供了一种新型的（）SrtA抑制剂，并且是治疗水产养殖中（）感染的一个有前景的候选药物。
