Inactivation of GH3.5 by COP1-mediated K63-linked ubiquitination promotes seedling hypocotyl elongation.

ABSTRACT: CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1), which was first discovered as a central repressor of photomorphogenesis in Arabidopsis, destabilizes proteins by ubiquitination in both plants and animals. However, it is unclear whether and how Arabidopsis COP1 mediates non-proteolytic ubiquitination to regulate photomorphogenesis. Here, we show that COP1-mediated lysine 63 (K63)-linked polyubiquitination inhibits the enzyme activity of GRETCHEN HAGEN 3.5 (GH3.5), a synthetase that conjugates amino acids to indole-3-acetic acid (IAA), thereby promoting hypocotyl elongation in the dark. We show that COP1 physically interacts with and genetically acts through GH3.5 to promote hypocotyl elongation. COP1 does not affect GH3.5 protein stability; however, it suppresses GH3.5 activity through K63-linked

SUBMITTER: Liu Y 

PROVIDER: S-EPMC11997217 | biostudies-literature | 2025 Apr

REPOSITORIES: biostudies-literature