Heessen Stijn, Dantuma Nico P, Tessarz Peter, Jellne Marianne, Masucci Maria G
Microbiology and Tumor Biology Center, Karolinska Institutet, Box 280, S-171 77 Stockholm, Sweden.
FEBS Lett. 2003 Dec 4;555(2):397-404. doi: 10.1016/s0014-5793(03)01296-1.
The glycine-alanine (GA) repeat of the Epstein-Barr virus nuclear antigen-1 inhibits in cis ubiquitin-dependent proteolysis in mammalian cells through a yet unknown mechanism. In the present study we demonstrate that the GA repeat targets an evolutionarily conserved step in proteolysis since it can prevent the degradation of proteasomal substrates in the yeast Saccharomyces cerevisiae. Insertion of yeast codon-optimised recombinant GA (rGA) repeats of different length in green fluorescent protein reporters harbouring N-end rule or ubiquitin fusion degradation signals resulted in efficient stabilisation of these substrates. Protection was also achieved in rpn10delta yeast suggesting that this polyubiquitin binding protein is not required for the rGA effect. The conserved effect of the GA repeat in yeast opens the possibility for the use of genetic screens to unravel its mode of action.
爱泼斯坦-巴尔病毒核抗原1的甘氨酸-丙氨酸（GA）重复序列通过一种尚不清楚的机制抑制哺乳动物细胞中顺式泛素依赖性蛋白水解。在本研究中，我们证明GA重复序列靶向蛋白水解中一个进化上保守的步骤，因为它可以防止酿酒酵母中蛋白酶体底物的降解。在携带N端规则或泛素融合降解信号的绿色荧光蛋白报告基因中插入不同长度的酵母密码子优化重组GA（rGA）重复序列，可有效稳定这些底物。在rpn10δ酵母中也实现了保护，这表明这种多聚泛素结合蛋白对于rGA效应不是必需的。GA重复序列在酵母中的保守效应为利用遗传筛选来揭示其作用模式提供了可能性。
