Abstract：
Phenamacril (PHA) is a highly selective fungicide for controlling fusarium head blight (FHB) mainly caused by F. graminearum and F. asiaticum. However, the C423A mutation in myosin I of F. graminearum (FgMyoI) leads to natural resistance to PHA. Here, based on the computational approaches and biochemical validation, we elucidate the atomic-level mechanism behind the natural resistance of F. graminearum to the fungicide PHA due to the C423A mutation in FgMyoI. The mutation leads to a rearrangement of pocket residues, resulting in increased size and flexibility of the binding pocket, which impairs the stable binding of PHA. MST experiments confirm that the mutant protein FgMyoIC423A exhibits significantly reduced affinity for PHA compared to wild-type FgMyoI and the nonresistant C423K mutant. This decreased binding affinity likely underlies the development of PHA resistance in F. graminearum. Conversely, the nonresistant C423K mutant retains sensitivity to PHA due to the introduction of a strong hydrogen bond donor, which facilitates stable binding of PHA in the pocket. These findings shed light on the molecular basis of PHA resistance and provide new directions for the creation of new myosin inhibitors.
摘要：
Phenamacril（PHA）是一种高度选择性的杀菌剂，可用于控制主要由F.graminearum和asiaticum引起的枯萎病（FHB）。然而,谷草的肌球蛋白I（FgMyoI）中的C423A突变导致对PHA的天然抗性。这里,基于计算方法和生化验证，我们阐明了由于FgMyoI中的C423A突变而导致的谷草对杀菌剂PHA的天然抗性背后的原子级机制。突变导致口袋残基的重排，导致装订口袋的尺寸和灵活性增加，这损害了PHA的稳定结合。MST实验证实,与野生型FgMyoI和非抗性C423K突变体相比,突变蛋白FgMyoIC423A表现出对PHA的显著降低的亲和力。这种降低的结合亲和力可能是在禾谷镰刀菌中产生PHA抗性的基础。相反，由于引入了强的氢键供体，非抗性C423K突变体保留了对PHA的敏感性，这有利于PHA在口袋中的稳定结合。这些发现揭示了PHA抗性的分子基础，并为新的肌球蛋白抑制剂的产生提供了新的方向。
