School of Life Sciences, Gwangju Institute of Science & Technology (GIST), Gwangju, Republic of Korea.
FEBS Lett. 2011 Dec 15;585(24):3959-63. doi: 10.1016/j.febslet.2011.11.002. Epub 2011 Nov 10.
In this study using non-reduced/reduced 2-dimensional electrophoresis (NR/R-2DE), we clearly demonstrated that E3-independent ubiquitination by Ube2K produced not only unanchored but also Ube2K-linked polyubiquitins through thioester and isopeptide bonds. E3-independent assembly of polyubiquitins on the catalytic cysteine of Ube2K strongly supports the possibility of 'en bloc transfer' for polyubiquitination. From the same analyses of E3-independent ubiquitination products by other E2s, we also found that different lengths of polyubiquitins were linked to different E2s through thioester bond; longer chains by Cdc34 like Ube2K, short chains by Ube2g2, and mono-ubiquitin by UbcH10. Our results suggest that E2s possess the different intrinsic catalytic activities for polyubiquitination.
在这项使用非还原/还原二维电泳（NR/R-2DE）的研究中，我们清楚地表明，Ube2K 介导的 E3 非依赖性泛素化不仅产生了非锚定的泛素，还通过硫酯键和异肽键产生了 Ube2K 连接的多泛素。Ube2K 上催化半胱氨酸上的多泛素的 E3 非依赖性组装强烈支持了“整体转移”进行多泛素化的可能性。从其他 E2 对 E3 非依赖性泛素化产物的相同分析中，我们还发现不同长度的多泛素通过硫酯键连接到不同的 E2 上；像 Ube2K 这样的 Cdc34 连接更长的链，Ube2g2 连接短链，UbcH10 连接单泛素。我们的结果表明，E2 具有不同的内在多泛素化催化活性。
