HYL1-CLEAVAGE SUBTILASE 1 (HCS1) suppresses miRNA biogenesis in response to light-to-dark transition

Proc Natl Acad Sci U S A. 2022 Feb 8;119(6):e2116757119. doi: 10.1073/pnas.2116757119.

Abstract

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.

Keywords: COP1 E3 ligase; HYL1 proteostasis; light/dark transition; miRNA biogenesis; subtilisin-like protease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / metabolism*
  • Cell Cycle Proteins / metabolism
  • Cell Nucleus / metabolism
  • Gene Expression Regulation, Plant / physiology
  • MicroRNAs / metabolism*
  • Plant Leaves / metabolism
  • RNA Processing, Post-Transcriptional / physiology*
  • RNA-Binding Proteins / metabolism
  • Ubiquitin-Protein Ligases / metabolism

Substances

  • Arabidopsis Proteins
  • Cell Cycle Proteins
  • MicroRNAs
  • RNA-Binding Proteins
  • Ubiquitin-Protein Ligases