Rapid Reversion from Monomer to Dimer Regenerates the Ultraviolet-B Photoreceptor UV RESISTANCE LOCUS8 in Intact Arabidopsis Plants
Rapid Reversion from Monomer to Dimer Regenerates the Ultraviolet-B Photoreceptor UV RESISTANCE LOCUS8 in Intact Arabidopsis Plants
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DOI：
10.1104/pp.112.206805
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发表时间：
2013-01-01
期刊：
影响因子：
7.4
通讯作者：
Jenkins, Gareth I.
中科院分区：
文献类型：
--
作者：
Heilmann, Monika;Jenkins, Gareth I.
拟南芥抗紫外线LOCUS8(UVR8)是一种光感受器，能特异性地介导植物对紫外线B的光形态建成反应。UV-B光接收诱导UVR8二聚体转化为单体，该单体与构成光形态发生蛋白1(COP1)相互作用，调节基因表达。然而，还不知道二聚体感光器是如何在植物中再生的。在这里，我们表明，通过使用蛋白质合成和降解的抑制剂通过蛋白酶体，UVR8二聚体在单体被破坏后不能通过快速从头合成再生。相反，再生是通过从单体返回到二聚体来进行的。然而，在UV-B照射后的黑暗中，二聚体UVR8在体内的再生速度比在有光照的植物提取物或纯化的UVR8的体外再生快得多，这表明快速再生需要完整的细胞。体内二聚体的快速再生需要蛋白质的合成，UVR8的羧基末端27个氨基酸区域的存在，以及已知与羧基末端区域相互作用的COP1的存在。然而，这些因素都不能完全解释体内和体外再生动力学的差异，表明体内UVR8二聚体再生涉及额外的蛋白质或过程。
Arabidopsis (Arabidopsis thaliana) UV RESISTANCE LOCUS8 (UVR8) is a photoreceptor that specifically mediates photomorphogenic responses to ultraviolet (UV)-B in plants. UV-B photoreception induces the conversion of the UVR8 dimer into a monomer that interacts with the CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1) protein to regulate gene expression. However, it is not known how the dimeric photoreceptor is regenerated in plants. Here, we show, by using inhibitors of protein synthesis and degradation via the proteasome, that the UVR8 dimer is not regenerated by rapid de novo synthesis following destruction of the monomer. Rather, regeneration occurs by reversion from the monomer to the dimer. However, regeneration of dimeric UVR8 in darkness following UV-B exposure occurs much more rapidly in vivo than in vitro with illuminated plant extracts or purified UVR8, indicating that rapid regeneration requires intact cells. Rapid dimer regeneration in vivo requires protein synthesis, the presence of a carboxyl-terminal 27-amino acid region of UVR8, and the presence of COP1, which is known to interact with the carboxyl-terminal region. However, none of these factors can account fully for the difference in regeneration kinetics in vivo and in vitro, indicating that additional proteins or processes are involved in UVR8 dimer regeneration in vivo.