Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
J Adv Res. 2024 May;59:1-17. doi: 10.1016/j.jare.2023.06.007. Epub 2023 Jun 18.
In yeast, the cytoplasm-to-vacuole targeting (Cvt) pathway acts as a biosynthetic autophagy-related process, in which vacuolar targeting of hydrolase is mediated by the machineries involved in the selective autophagy. However, the mechanistic insights into vacuolar targeting of hydrolases through the selective autophagy pathway still remain enigmatic in filamentous fungi.
Our study aims to investigate the mechanisms involved in vacuolar targeting of hydrolases in filamentous fungi.
The filamentous entomopathogenic fungus Beauveria bassiana was used as a representative of filamentous fungi. We identified the homologs of yeast aminopeptidase I (Ape1) in B. bassiana by bioinformatic analyses and characterized their physiological roles by gene function analyses. Pathways for vacuolar targeting of hydrolases were investigated via molecular trafficking analyses.
B. bassiana has two homologs of yeast aminopeptidase I (Ape1) which are designated as BbApe1A and BbApe1B. The two homologs of yeast Ape1 contribute to starvation tolerance, development, and virulence in B. bassiana. Significantly, BbNbr1 acts as a selective autophagy receptor to mediate the vacuolar targeting of the two Ape1 proteins, in which BbApe1B interacts with BbNbr1 also directly interacting with BbAtg8, and BbApe1A has an additional requirement of the scaffold protein BbAtg11 that interacts with BbNbr1 and BbAtg8. Protein processing occurs at both terminuses of BbApe1A and only at carboxyl terminus of BbApe1B, which is also dependent on the autophagy-related proteins. Together, the functions and translocation processes of the two Ape1 proteins are associated with autophagy in fungal lifecycle.
This study reveals the functions and translocation processes for vacuolar hydrolases in the insect-pathogenic fungi and improves our understandings of the Nbr1-mediated vacuolar targeting pathway in the filamentous fungi.
在酵母中，细胞质到液泡靶向（Cvt）途径充当生物合成自噬相关过程，其中水解酶的液泡靶向由参与选择性自噬的机制介导。然而，丝状真菌中通过选择性自噬途径对水解酶进行液泡靶向的机制见解仍然神秘莫测。
我们的研究旨在研究丝状真菌中水解酶的液泡靶向涉及的机制。
使用昆虫病原丝状真菌球孢白僵菌作为丝状真菌的代表。我们通过生物信息学分析鉴定了球孢白僵菌中酵母氨肽酶 I（Ape1）的同源物，并通过基因功能分析表征了它们的生理作用。通过分子运输分析研究了水解酶的液泡靶向途径。
球孢白僵菌有两个酵母氨肽酶 I（Ape1）的同源物，分别命名为 BbApe1A 和 BbApe1B。两个酵母 Ape1 的同源物有助于球孢白僵菌的耐饥饿、发育和毒力。重要的是，BbNbr1 作为选择性自噬受体介导两种 Ape1 蛋白的液泡靶向，其中 BbApe1B 与 BbNbr1 直接相互作用，也与 BbAtg8 相互作用，而 BbApe1A 还需要与 BbNbr1 和 BbAtg8 相互作用的支架蛋白 BbAtg11。BbApe1A 的两个末端都发生蛋白加工，而只有 BbApe1B 的羧基末端发生蛋白加工，这也依赖于自噬相关蛋白。总之，两种 Ape1 蛋白的功能和易位过程与真菌生命周期中的自噬有关。
本研究揭示了昆虫病原真菌中液泡水解酶的功能和易位过程，提高了我们对丝状真菌中 Nbr1 介导的液泡靶向途径的认识。
