Datta Sourav, Hettiarachchi G H C M, Deng Xing-Wang, Holm Magnus
Department of Cell and Molecular Biology, Gothenburg University, Sweden.
Plant Cell. 2006 Jan;18(1):70-84. doi: 10.1105/tpc.105.038182. Epub 2005 Dec 9.
CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) is an E3 ubiquitin ligase that represses photomorphogenesis in the dark. Therefore, proteins interacting with COP1 could be important regulators of light-dependent development. Here, we identify CONSTANS-LIKE3 (COL3) as a novel interaction partner of COP1. A green fluorescent protein-COL3 fusion protein colocalizes with COP1 to nuclear speckles when transiently expressed in plant cells. This localization requires the B-box domains in COL3, indicating a novel function of this domain. A loss-of-function col3 mutant has longer hypocotyls in red light and in short days. Unlike constans, the col3 mutant flowers early and shows a reduced number of lateral branches in short days. The mutant also exhibits reduced formation of lateral roots. The col3 mutation partially suppresses the cop1 and deetiolated1 (det1) mutations in the dark, suggesting that COL3 acts downstream of both of these repressors. However, the col3 mutation exerts opposing effects on cop1 and det1 in terms of lateral roots and anthocyanin accumulation, suggesting that COL3 also has activities that are independent of COP1 and DET1. In conclusion, we have identified COL3 as a positive regulator of photomorphogenesis that acts downstream of COP1 but can promote lateral root development independently of COP1 and also function as a daylength-sensitive regulator of shoot branching.
组成型光形态建成1（COP1）是一种E3泛素连接酶，在黑暗中抑制光形态建成。因此，与COP1相互作用的蛋白质可能是光依赖发育的重要调节因子。在此，我们鉴定出CONSTANS-LIKE3（COL3）是COP1的一种新的相互作用伙伴。当在植物细胞中瞬时表达时，绿色荧光蛋白-COL3融合蛋白与COP1共定位于核斑点。这种定位需要COL3中的B-box结构域，表明该结构域具有新功能。功能缺失的col3突变体在红光下和短日照条件下具有更长的下胚轴。与CONSTANS不同，col3突变体开花早，在短日照条件下侧枝数量减少。该突变体还表现出侧根形成减少。col3突变在黑暗中部分抑制了cop1和去黄化1（det1）突变，表明COL3在这两种抑制因子的下游起作用。然而，col3突变在侧根和花青素积累方面对cop1和det1产生相反的影响，表明COL3也具有独立于COP1和DET1的活性。总之，我们已鉴定出COL3是光形态建成的正调节因子，它在COP1下游起作用，但可独立于COP1促进侧根发育，并且还作为枝条分枝的日长敏感调节因子发挥作用。
