Chaperone-like protein DAY plays critical roles in photomorphogenesis

Ho-Seok Lee,Huikyong Cho,Jae-Hee Kim,Youssef Belkhadir,Young Jeon,Man-Ho Oh,Jung-Min Lee,Julian Bünting,Sunghee Lee,Tae-Wuk Kim,Tak Lee,Hyun-Sook Pai,Insuk Lee,Jiwoo Kim,Hee-Kyung Ahn,Ilyeong Choi,Dong Hye Seo,Du-Hwa Lee

doi:10.1038/s41467-021-24446-5

Abstract

Photomorphogenesis, light-mediated development, is an essential feature of all terrestrial plants. While chloroplast development and brassinosteroid (BR) signaling are known players in photomorphogenesis, proteins that regulate both pathways have yet to be identified. Here we report that DE-ETIOLATION IN THE DARKANDYELLOWING IN THE LIGHT (DAY), a membrane protein containing DnaJ-like domain, plays a dual-role in photomorphogenesis by stabilizing the BR receptor, BRI1, as well as a key enzyme in chlorophyll biosynthesis, POR. DAY localizes to both the endomembrane and chloroplasts via its first transmembrane domain and chloroplast transit peptide, respectively, and interacts with BRI1 and POR in their respective subcellular compartments. Using genetic analysis, we show that DAY acts independently on BR signaling and chlorophyll biogenesis. Collectively, this work uncovers DAY as a factor that simultaneously regulates BR signaling and chloroplast development, revealing a key regulator of photomorphogenesis that acts across cell compartments.

Highlights

Photomorphogenesis, light-mediated development, is an essential feature of all terrestrial plants
Deletion of the N-lobe from the BRASSINOSTEROID INSENSITIVE 1 (BRI1) kinase domain (KD) significantly reduced the interaction with maltose-binding protein (MBP)-▵chloroplast transit peptide (cTP), suggesting the importance of the N-terminal lobe (Nlobe) sequence for the interaction (Fig. 5e). These results suggest that the N-lobe of BRI1 KD and the cTP of DARK AND YELLOWING IN THE LIGHT (DAY) may be critical for interactions between DAY and BRI1 KD
We find that DAY localizes to the chloroplast through its cTP and to the endomembrane via its first transmembrane domain

Summary

Introduction

Photomorphogenesis, light-mediated development, is an essential feature of all terrestrial plants. We report that DE-ETIOLATION IN THE DARK AND YELLOWING IN THE LIGHT (DAY), a membrane protein containing DnaJ-like domain, plays a dual-role in photomorphogenesis by stabilizing the BR receptor, BRI1, as well as a key enzyme in chlorophyll biosynthesis, POR. Illumination of dark-grown seedlings triggers chlorophyll biosynthesis, and the subsequent conversion of etioplasts into photosynthetically active chloroplasts, leading to cotyledon greening[3,24,25]. Illumination triggers degradation of POR and breakdown of PLBs, in parallel with chlorophyll synthesis and chloroplast development[3,25] While these processes are critical to productive plant growth, a versatile factor capable of regulating the collective processes that comprise the switch to photomorphogenesis remains unknown. We focused on At3g51140, which has a DnaJlike (JL) domain characteristic for DnaJ/Hsp40-type cochaperones predicted to have holdase chaperone activity[26,30,31]

Methods

Results

Conclusion