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.
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|Publication status||Published - 2022 Feb 8|
Bibliographical noteFunding Information:
ACKNOWLEDGMENTS. We thank Nam-Chon Paek for providing cop1-4/ 35S:COP1WT-GFP and cop1-4/35S:COP1L170A-GFP transgenic plants. This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science, ICT (information and communications technology), and Future Planning (NRF-2020R1A2B5B01002592 and NRF-2018R1A6A1A03025607), and by Samsung Science and Technology Foundation Project SSTF-BA1801-09 (to S.W.Y.). This research was supported in part by NRF-2020R1I1A1A01073842 (to H.J.J.); and Brain Korea 21 (BK21) PLUS program fellowship awards to S.W.C., Y.K.O., M.K.H., C.M., and G.M.K.
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