The N-end rule pathway is a regulated protein degradation system. Arthrobotrys oligospora, a typical nematode-trapping fungus, switches its life strategies from saprophytism to carnivorism when capturing free-living nematodes by means of adhesive networks. In this study, a putative E3-ligase AoUBR1 involved in N-end rule pathway was characterized in A. oligospora during vegetative growth and trap formation. Expression of AoUBR1 coding gene was down-regulated during trap formation. Compared with wild type, the AoUBR1 knock-out mutants decreased the vegetative growth, formed less traps, and turned to be sensitive to cold stress, while, AoUBR1 overexpression mutants lost the capacity to produce conidia and also formed less traps. A number of genes differentially expressed by knock-out and overexpression of AoUBR1, which lead to the transcriptional responses associated with plasma membrane, transportation, oxidation, and proteolysis. AoUBR1 knock-out also resulted in the down-regulation of numerous secreted proteins associated with carnivorism and nutrient utilization from nematodes. In addition, AoUBR1 homologs were conserved in nematode-trapping fungi based on the genome searching. Therefore, the results suggested AoUBR1 in A. oligospora and its homologs in other trapping fungi are involved in the lifestyle switch between saprophytism and carnivorism.

N端规则途径是一个受调控的蛋白质降解系统。Arthrobotrys oligospora 是一种典型的捕捉线虫的真菌，在通过粘附网络捕获自由生活的线虫时，将其生活策略从腐生性转变为食肉性。在这项研究中，在营养生长和陷阱形成过程中，在A. oligospora中表征了一种假定的 E3-连接酶 AoUBR1，它参与了 N 端规则途径。AoUBR1 编码基因的表达在陷阱形成过程中被下调。与野生型相比，AoUBR1 基因敲除突变体的营养生长减少，陷阱减少，对冷胁迫敏感，而AoUBR1过表达突变体失去了产生分生孢子的能力，也形成了较少的陷阱。许多基因因AoUBR1的敲除和过表达而差异表达，导致与质膜、运输、氧化和蛋白水解相关的转录反应。AoUBR1敲除还导致与食肉性和线虫营养利用相关的许多分泌蛋白的下调。此外，基于基因组搜索，AoUBR1 同源物在捕获线虫的真菌中是保守的。因此，结果表明A. oligospora 中的AoUBR1及其在其他诱捕真菌中的同源物参与了腐生和食肉之间的生活方式转换。