Xu Xibing, Liang Ke, Li Haiyan, Liu Hao, Cao Qin, Shen Yan
College of Medicine, Henan University of Science and Technology, Luoyang 471000, China.
Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610064, China.
Biochem Biophys Res Commun. 2017 Sep 2;490(4):1232-1236. doi: 10.1016/j.bbrc.2017.06.198. Epub 2017 Jul 1.
Ubiquitin-like proteins (UBLs) are extremely well-conserved among eukaryotes and prokaryotes allowing interactions between proteins from different organisms. For example, the prokaryotic ubiquitin-like proteins (Pups) and the Proteasome accessory factor A (PafA) of Mycobacterium tuberculosis are sufficient to pupylate at least 51 Escherichia coli proteins. This work shows that the plant E3 ligases BnTR1 and AT1G02860 can ubiquitinate E. coli σ, but not Hsp70 DnaK in vitro. Molecular biology and biochemical studies confirm that the RING finger domain of BnTR1 and AT1G02860 is essential for their function. These results suggest that the substrates of plant E3 ligases can be prokaryotic protein and therefore the plant ubiquitylation system may have evolved from prokaryote.
泛素样蛋白（UBLs）在真核生物和原核生物中极其保守，使得来自不同生物体的蛋白质之间能够相互作用。例如，原核泛素样蛋白（Pups）和结核分枝杆菌的蛋白酶体辅助因子A（PafA）足以使至少51种大肠杆菌蛋白发生Pupylation修饰。这项研究表明，植物E3连接酶BnTR1和AT1G02860在体外可使大肠杆菌σ蛋白泛素化，但不能使热休克蛋白70（Hsp70）的DnaK蛋白泛素化。分子生物学和生化研究证实，BnTR1和AT1G02860的环状结构域对其功能至关重要。这些结果表明，植物E3连接酶的底物可以是原核蛋白，因此植物泛素化系统可能起源于原核生物。
