Functional characterization of wheat histone H2B monoubiquitination enzyme TaHUB2 in response to vernalization in Keumkang (Triticum aestivum L.)

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.