PCH1 and PCHL Directly Interact with PIF1, Promote Its Degradation, and Inhibit Its Transcriptional Function during Photomorphogenesis.

Abstract

PHOTOPERIODIC CONTROL OF HYPOCOTYL 1 (PCH1) and PCH1-LIKE (PCHL) were shown to directly bind to phytochrome B (phyB) and suppress phyB thermal reversion, resulting in plants with dramatically enhanced light sensitivity. Here, we show that PCH1 and PCHL also positively regulate various light responses, including seed germination, hypocotyl gravitropism, and chlorophyll biosynthesis, by physically interacting with PHYTOCHROME INTERACTING FACTOR 1 (PIF1) and CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1). PCH1 and PCHL interact with PIF1 both in the dark and light, and regulate PIF1 abundance. Moreover, PCH1 and PCHL facilitate the physical interaction between phyB and PIF1 in vivo to promote the light-induced degradation of PIF1. PCH1 and PCHL also inhibit the DNA-binding ability of PIF1 to negatively regulate the expressions of PIF1 target genes. In addition, PCH1 and PCHL interact with COP1 and undergo degradation through the 26S proteasome pathway in the dark. Consistently, pch1 suppresses cop1 phenotype in darkness. Collectively, our study reveals a novel mechanism by which PCH1 and PCHL regulate diverse light responses not only by stabilizing phyB Pfr form but also by directly interacting with PIF1 and COP1, providing a molecular understanding of the control of hypocotyl growth by these proteins.

• Authors: Mei-Chun Cheng, Beatrix Enderle, Praveen Kumar Kathare, Rafya Islam, Andreas Hiltbrunner, Enamul Huq
• Journal: Molecular plant (Mol Plant) Vol. 13 Issue 3 Pg. 499-514 (03 02 2020) ISSN: 1752-9867 [Electronic] England
• PMID: 32061894 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: Copyright © 2020 The Author. Published by Elsevier Inc. All rights reserved.

Chemical References

• Arabidopsis Proteins
• Basic Helix-Loop-Helix Transcription Factors
• F-Box Proteins
• PHOTOPERIODIC CONTROL OF HYPOCOTYL 1 protein, Arabidopsis
• PIF1 protein, Arabidopsis
• Transcription Factors
• AT2G32950 protein, Arabidopsis
• Ubiquitin-Protein Ligases

Topics

• Arabidopsis (genetics, growth & development, metabolism, radiation effects)
• Arabidopsis Proteins (genetics, metabolism)
• Basic Helix-Loop-Helix Transcription Factors (genetics, metabolism)
• Darkness
• F-Box Proteins (metabolism)
• Plant Development (genetics, radiation effects)
• Protein Binding (radiation effects)
• Proteolysis (radiation effects)
• Transcription Factors (metabolism)
• Transcription, Genetic
• Ubiquitin-Protein Ligases (metabolism)