The S. pombe translation initiation factor eIF4G is Sumoylated and associates with the SUMO protease Ulp2.
The S. pombe translation initiation factor eIF4G is Sumoylated and associates with the SUMO protease Ulp2.
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DOI：
10.1371/journal.pone.0094182
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Watts FZ
中科院分区：
文献类型：
--
作者：
Jongjitwimol J;Feng M;Zhou L;Wilkinson O;Small L;Baldock R;Taylor DL;Smith D;Bowler LD;Morley SJ;Watts FZ
SUMO是一种小的翻译后修饰物，它附着在靶蛋白的赖氨酸残基上。它通过改变蛋白质-蛋白质相互作用、蛋白质定位和蛋白质活性发挥作用。SUMO链也可以作为泛素化的底物，导致蛋白酶体介导的靶蛋白降解。SUMO通过多种特异性蛋白酶之一从靶蛋白中去除。类小泛素化和去类小泛素化的过程在DNA代谢和染色质结构的维持中具有良好的记录作用。为了进一步分析这种修饰的作用，我们纯化了含有S.粟酒酵母SUMO蛋白酶，Ulp 2.这些复合物含有核糖体生物合成、RNA稳定性和蛋白质合成所需的蛋白质。在这里，我们集中在两个翻译起始因子，我们确定为与Ulp 2，eIF 4G和eIF 3 h共纯化。我们证明了eIF 4G，而不是eIF 3 h，是sumoylated。这种修饰在产生细胞质应激颗粒的条件下增加。与此一致，我们观察到应激细胞中eIF 4G和SUMO的部分共定位。使用HeLa细胞，我们证明了人eIF 4GI也被sumoylated;体外研究表明，人eIF 4GI在K1368和K1588上被修饰，这两个位点分别位于C-末端eIF 4A和Mnk结合位点。
SUMO is a small post-translational modifier, that is attached to lysine residues in target proteins. It acts by altering protein-protein interactions, protein localisation and protein activity. SUMO chains can also act as substrates for ubiquitination, resulting in proteasome-mediated degradation of the target protein. SUMO is removed from target proteins by one of a number of specific proteases. The processes of sumoylation and desumoylation have well documented roles in DNA metabolism and in the maintenance of chromatin structure. To further analyse the role of this modification, we have purified protein complexes containing the S. pombe SUMO protease, Ulp2. These complexes contain proteins required for ribosome biogenesis, RNA stability and protein synthesis. Here we have focussed on two translation initiation factors that we identified as co-purifying with Ulp2, eIF4G and eIF3h. We demonstrate that eIF4G, but not eIF3h, is sumoylated. This modification is increased under conditions that produce cytoplasmic stress granules. Consistent with this we observe partial co-localisation of eIF4G and SUMO in stressed cells. Using HeLa cells, we demonstrate that human eIF4GI is also sumoylated; in vitro studies indicate that human eIF4GI is modified on K1368 and K1588, that are located in the C-terminal eIF4A- and Mnk-binding sites respectively.
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