Wang Pengcheng, Guo Kai, Su Qian, Deng Jinwu, Zhang Xianlong, Tu Lili
National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
Plant J. 2022 May;110(4):1005-1020. doi: 10.1111/tpj.15716. Epub 2022 Mar 31.
Ubiquitination plays a vital role in modifying protein activity and destiny. Ub-conjugating enzyme E2 is one of the enzymes that participates in this precise process. There are at least 169 E2 proteins in the allotetraploid cotton (Gossypium hirsutum), but their function remains unknown. Here we identify an E2 gene GhUBC2L and show its positive role in cell proliferation and expansion. Complete knock-down of GhUBC2L in cotton resulted in retarded growth and reduced organ size. Conversely, overexpression of GhUBC2L promoted cotton growth, generating enlarged organs in size. Monoubiquitination of H2A and H2B was strongly impaired in GhUBC2L-suppressed cotton but slightly enhanced in GhUBC2L-overexpressed plant. GhUbox8, a U-box type E3 ligase protein, was found to interact with GhUBC2L both in vivo and in vitro, indicating their synergistical function in protein ubiquitination. Furthermore, GhUbox8 was shown to interact with a series of histone proteins, including histone H2A and H2B, indicating its potential monoubiquitination on H2A and H2B. Expression of genes relating to cell cycle and organ development were altered when the expression of GhUBC2L was changed. Our results show that GhUBC2L modulates histone monoubiquitination synergistically with GhUbox8 to regulate the expression of genes involved in organ development and cell cycle, thus controlling organ size in cotton. This research provides new insights into the role of protein ubiquitination in organ size control. Histone monoubiquitination plays an important role in plant development. Here, we identified an E2 enzyme GhUBC2L that modulates histone monoubiquitination synergistically with an E3 ligase GhUbox8 to mediate organ size control in cotton.
泛素化在调节蛋白质活性和命运方面发挥着至关重要的作用。泛素结合酶E2是参与这一精确过程的酶之一。在异源四倍体棉花（陆地棉）中至少有169种E2蛋白，但其功能仍然未知。在此，我们鉴定了一个E2基因GhUBC2L，并展示了其在细胞增殖和扩展中的积极作用。棉花中GhUBC2L的完全敲低导致生长迟缓以及器官大小减小。相反，GhUBC2L的过表达促进了棉花生长，使器官尺寸增大。在GhUBC2L抑制的棉花中，H2A和H2B的单泛素化受到严重损害，但在GhUBC2L过表达的植株中略有增强。发现一种U-box型E3连接酶蛋白GhUbox8在体内和体外均与GhUBC2L相互作用，表明它们在蛋白质泛素化中具有协同功能。此外，GhUbox8被证明与一系列组蛋白相互作用，包括组蛋白H2A和H2B，表明其对H2A和H2B具有潜在的单泛素化作用。当GhUBC2L的表达发生变化时，与细胞周期和器官发育相关的基因表达也会改变。我们的结果表明，GhUBC2L与GhUbox8协同调节组蛋白单泛素化，以调控参与器官发育和细胞周期的基因表达，从而控制棉花的器官大小。这项研究为蛋白质泛素化在器官大小控制中的作用提供了新的见解。组蛋白单泛素化在植物发育中起着重要作用。在此，我们鉴定了一种E2酶GhUBC2L，它与E3连接酶GhUbox8协同调节组蛋白单泛素化，以介导棉花的器官大小控制。
