ABSTRACT

Histone monoubiquitination has an important role in the regulation of DNA replication, repair, and transcription in plants. Here, we report the molecular function of wheat histone H2B monoubiquitination enzyme 2 (TaHUB2). The full length of TaHUB2 contains a Really Interesting New Gene (RING) domain and its encoded protein was localized in both nucleus and cytoplasm. We also find TaHUB2 directly interacts with histone H2B in yeast and tobacco. The transcription level of TaHUB2 was decreased as the increased vernalization periods until 50 d. The TaHUB2 exhibited ubiquitination activities and were rapidly degraded in the cell-free extracts with apparently 3–6 h after vernalization compared with non-vernalization. Moreover, histone H2B was mono-ubiquitinated by TaHUB2 and ubiquitylated histone H2B (H2Bub1) level was decreased after vernalization conditions in wheat. These results provide novel information for understanding the molecular characterization of wheat RING-type E3 ligase and their possible roles.

摘要

组蛋白单泛素化在调节植物的DNA复制，修复和转录中具有重要作用。在这里，我们报告小麦组蛋白H2B单泛素化酶2（TaHUB2）的分子功能。TaHUB2的全长包含一个真正有趣的新基因（RING）域，其编码的蛋白质位于细胞核和细胞质中。我们还发现TaHUB2与酵母和烟草中的组蛋白H2B直接相互作用。随着春化时间的延长，TaHUB2的转录水平降低到50 d。与未进行春化处理相比，TaHUB2表现出泛素化活性，并在无细胞提取物中明显降解，大约在春化后3–6小时内降解。而且，在小麦春化条件下，组蛋白H2B被TaHUB2单泛素化，泛素化的组蛋白H2B（H2Bub1）水平降低。这些结果为了解小麦RING型E3连接酶的分子特征及其可能的作用提供了新的信息。