核心工厂微处理器由DICER-LIKE1(DCL1)组成,SERRATE(SE),和低血压叶1(HYL1),并在microRNA(miRNA)生物发生中起关键作用。然而,每个组件的蛋白水解调节仍然难以捉摸。这里,我们显示HYL1-CLEAVAGESubBTILase1(HCS1)是HYL1-去稳定的细胞质蛋白酶。HCS1过量减少HYL1,破坏miRNA生物发生,而HCS1缺乏积累HYL1。始终如一,我们鉴定了对HCS1蛋白水解活性不敏感的HYL1K154A突变体,证实了HCS1在HYL1蛋白抑制中的重要性.此外,HCS1活性受光/暗转变调节。在灯光下,细胞质本构光合组织1(COP1)E3连接酶抑制HCS1活性。COP1通过阻碍HYL1进入HCS1的催化位点而在空间上抑制HCS1。相比之下,由于COP1核重新定位,黑暗解除了HCS1对HYL1不稳定的束缚。总的来说,COP1-HYL1-HCS1网络可能整合了两条重要的细胞通路:miRNA-生物基因通路和光信号通路.
The core plant microprocessor consists of DICER-LIKE 1 (DCL1), SERRATE (SE), and HYPONASTIC LEAVES 1 (HYL1) and plays a pivotal role in microRNA (miRNA) biogenesis. However, the proteolytic regulation of each component remains elusive. Here, we show that HYL1-CLEAVAGE SUBTILASE 1 (HCS1) is a cytoplasmic protease for HYL1-destabilization. HCS1-excessiveness reduces HYL1 that disrupts miRNA biogenesis, while HCS1-deficiency accumulates HYL1. Consistently, we identified the HYL1K154A mutant that is insensitive to the proteolytic activity of HCS1, confirming the importance of HCS1 in HYL1 proteostasis. Moreover, HCS1-activity is regulated by light/dark transition. Under light, cytoplasmic CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) E3 ligase suppresses HCS1-activity. COP1 sterically inhibits HCS1 by obstructing HYL1 access into the catalytic sites of HCS1. In contrast, darkness unshackles HCS1-activity for HYL1-destabilization due to nuclear COP1 relocation. Overall, the COP1-HYL1-HCS1 network may integrate two essential cellular pathways: the miRNA-biogenetic pathway and light signaling pathway.