National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
Mol Plant. 2012 Jan;5(1):85-97. doi: 10.1093/mp/ssr052. Epub 2011 Jul 16.
CRYPTOCHROMES (CRYs) are photolyase-like ultraviolet-A/blue light photoreceptors that mediate various light responses in plants. The signaling mechanism of Arabidopsis CRYs (CRY1 and CRY2) involves direct CRY-COP1 interaction. Here, we report that CRY1(G380R), which carries a Gly-to-Arg substitution of the highly conserved G380 in the photolyase-related (PHR) domain of Arabidopsis CRY1, shows constitutive CRY1 photoreceptor activity in Arabidopsis. Transgenic plants overexpressing CRY1(G380R) display a constitutively photomorphogenic (COP) phenotype in darkness, as well as a dramatic early flowering phenotype under short-day light conditions (SD). We further demonstrate that CRY1(G380R) expression driven by the native CRY1 promoter also results in a COP phenotype in darkness. Moreover, overexpression of either the Arabidopsis homolog CRY2(G377R) or the rice ortholog OsCRY1b(G388R) of CRY1(G380R) in Arabidopsis results in a COP phenotype in darkness. Cellular localization studies indicate that CRY1(G380R) co-localizes with COP1 in the same nuclear bodies (NBs) in vivo and inhibits the nuclear accumulation of COP1 in darkness. These results suggest that the conserved G380 may play a critical role in regulating the photoreceptor activity of plant CRYs and that CRY1(G380R) might constitutively phenocopy the photo-activated CRY1 in darkness and thus constitutively mediate CRY1 signaling.
隐花色素（CRYs）是光解酶样的紫外 A/蓝光光受体，介导植物中的各种光响应。拟南芥 CRYs（CRY1 和 CRY2）的信号机制涉及直接的 CRY-COP1 相互作用。在这里，我们报告了 CRY1(G380R)，它携带了拟南芥 CRY1 光解酶相关（PHR）结构域中高度保守的 G380 的甘氨酸到精氨酸取代，在拟南芥中表现出组成型 CRY1 光受体活性。过表达 CRY1(G380R)的转基因植物在黑暗中表现出组成型光形态建成（COP）表型，以及在短日照光条件下（SD）表现出明显的早花表型。我们进一步证明，由天然 CRY1 启动子驱动的 CRY1(G380R)表达也会导致黑暗中的 COP 表型。此外，在拟南芥中过表达拟南芥同源物 CRY2(G377R)或水稻同源物 OsCRY1b(G388R)的 CRY1(G380R)也会导致黑暗中的 COP 表型。细胞定位研究表明，CRY1(G380R)在体内与 COP1 共定位于相同的核体（NBs）中，并抑制 COP1 在黑暗中的核积累。这些结果表明，保守的 G380 可能在调节植物 CRYs 的光受体活性中发挥关键作用，并且 CRY1(G380R)可能在黑暗中组成型模拟光激活的 CRY1，从而组成型介导 CRY1 信号。
