Tan Wei, Wang Zheng, Prelich Gregory
Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461.
Department of Genetics, Albert Einstein College of Medicine, Bronx, New York 10461
G3 (Bethesda). 2013 Apr 9;3(4):771-780. doi: 10.1534/g3.113.005827.
The Slx5-Slx8 complex is a ubiquitin ligase that preferentially ubiquitylates SUMOylated substrates, targeting them for proteolysis. Mutations in SLX5, SLX8, and other SUMO pathway genes were previously identified in our laboratory as genomic suppressors of a point mutation (mot1-301) in the transcriptional regulator MOT1 To further understand the links between the SUMO and ubiquitin pathways, a screen was performed for high-copy suppressors of mot1-301, yielding three genes (MOT3, MIT1, and ULS1). MOT3 and MIT1 have characteristics of prions, and ULS1 is believed to encode another SUMO-targeted ubiquitin ligase (STUbL) that functionally overlaps with Slx5-Slx8. Here we focus on ULS1, obtaining results suggesting that the relationship between ULS1 and SLX5 is more complex than expected. Uls1 interacted with Slx5 physically in to yeast two-hybrid and co-immunoprecipitation assays, a uls1 mutation that blocked the interaction between Uls1 and Slx5 interfered with ULS1 function, and genetic analyses indicated an antagonistic relationship between ULS1 and SLX5 Combined, our results challenge the assumption that Uls1 and Slx5 are simply partially overlapping STUbLs and begin to illuminate a regulatory relationship between these two proteins.
Slx5-Slx8复合物是一种泛素连接酶，它优先使SUMO化的底物泛素化，将它们靶向进行蛋白水解。我们实验室之前在转录调节因子MOT1中的一个点突变（mot1-301）的基因组抑制子中鉴定出SLX5、SLX8和其他SUMO途径基因的突变。为了进一步了解SUMO和泛素途径之间的联系，我们对mot1-301的高拷贝抑制子进行了筛选，得到了三个基因（MOT3、MIT1和ULS1）。MOT3和MIT1具有朊病毒的特征，并且ULS1被认为编码另一种与Slx5-Slx8功能重叠的SUMO靶向泛素连接酶（STUbL）。在这里，我们聚焦于ULS1，获得的结果表明ULS1和SLX5之间的关系比预期更复杂。在酵母双杂交和免疫共沉淀实验中，Uls1与Slx5发生物理相互作用，一个阻断Uls1和Slx5之间相互作用的uls1突变干扰了ULS1的功能，并且遗传分析表明ULS1和SLX5之间存在拮抗关系。综合来看，我们的结果挑战了Uls1和Slx5仅仅是部分重叠的STUbL的假设，并开始阐明这两种蛋白质之间的调控关系。
