Small GTPases of the ADP-ribosylation factor (Arf) family and their activating proteins (Arf-GAPs) regulate mycelial development and pathogenicity in yeast and filamentous fungi; however, little is known about their roles in nematode-trapping (NT) fungi. In this study, an ortholog of Arf-GAP Glo3 (AoGlo3) in Saccharomyces cerevisiae was characterized in the NT fungus Arthrobotrys oligospora. Deletion of the Aoglo3 gene resulted in growth defects and an increase in hyphal septum. Meanwhile, the sporulation capacity of the ΔAoglo3 mutant was decreased by 98%, and 67.1-71.2% spores became gourd or claviform in shape (from obovoid), which was accompanied by a significant decrease in the spore germination rate. This reduced sporulation capacity correlated with the transcriptional repression of several sporulation-related genes including fluG, rodA, abaA, medA, and lreA. The ΔAoglo3 mutant was also sensitive to several chemical stressors such as Congo red, NaCl, and sorbitol. Additionally, AoGlo3 was found to be involved in endocytosis, and more myelin figures were observed in the ΔAoglo3 mutant than in the wild-type strain, which was consistent with the presence of more autophagosomes observed in the mutant. Importantly, AoGlo3 affected the production of mycelial traps and serine proteases for nematode predation. In summary, AoGlo3 is involved in the regulation of multiple cellular processes such as mycelial growth, conidiation, environmental adaption, endocytosis, and pathogenicity in A. oligospora.

中文翻译：

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Arf-GAP AoGlo3调节捕获线虫的真菌节肢动物寡孢的分生孢子，内吞作用和致病性。

ADP-核糖基化因子（Arf）家族的小GTPases及其激活蛋白（Arf-GAP）调节酵母菌和丝状真菌的菌丝体发育和致病性；然而，关于它们在线虫捕获（NT）真菌中的作用了解甚少。在这项研究中，啤酒酵母中的Arf-GAP Glo3（AoGlo3）直系同源物在NT真菌Arthrobotrys oligospora中得到了表征。Aoglo3基因的删除导致生长缺陷和菌丝间隔增加。同时，ΔAoglo3突变体的孢子形成能力降低了98％，并且67.1-71.2％的孢子变成了葫芦状或楔形（从卵球形），伴随着孢子发芽率的显着降低。降低的孢子形成能力与几种与孢子形成相关的基因（包括fluG，rodA，abaA，medA和lreA。ΔAoglo3突变体还对几种化学胁迫源敏感，例如刚果红，NaCl和山梨糖醇。另外，发现AoGlo3参与了内吞作用，并且在ΔAoglo3突变体中观察到的髓磷脂比在野生型菌株中更多，这与在突变体中观察到的更多的自噬体一致。重要的是，AoGlo3影响了线虫捕食的菌丝体陷阱和丝氨酸蛋白酶的产生。总之，AoGlo3参与了多种细胞过程的调节，例如菌丝生长，分生，环境适应，内吞作用和少孢曲霉的致病性。与野生型菌株相比，ΔAoglo3突变体中观察到更多的髓磷脂图，这与突变体中观察到的更多自噬体一致。重要的是，AoGlo3影响了线虫捕食的菌丝体陷阱和丝氨酸蛋白酶的产生。总之，AoGlo3参与了多种细胞过程的调节，例如菌丝生长，分生，环境适应，内吞作用和少孢曲霉的致病性。在ΔAoglo3突变体中观察到的髓磷脂比在野生型菌株中更多，这与在突变体中观察到的更多的自噬体一致。重要的是，AoGlo3影响了线虫捕食的菌丝体陷阱和丝氨酸蛋白酶的产生。总之，AoGlo3参与了多种细胞过程的调节，例如菌丝生长，分生，环境适应，内吞作用和少孢曲霉的致病性。