CHLOROPLAST UNUSUAL POSITIONING 1 is a plant-specific actin polymerization factor regulating chloroplast movement

Plants have unique responses to fluctuating light conditions. One such response involves chloroplast photorelocation movement, which optimizes photosynthesis under weak light by the accumulation of chloroplasts along the periclinal side of the cell, which prevents photodamage under strong light by a...

Full description

Saved in:
Bibliographic Details
Published in:The Plant cell 2024-03, Vol.36 (4), p.1159-1181
Main Authors: Kong, Sam-Geun, Yamazaki, Yosuke, Shimada, Atsushi, Kijima, Saku T, Hirose, Keiko, Katoh, Kaoru, Ahn, Jeongsu, Song, Hyun-Geun, Han, Jae-Woo, Higa, Takeshi, Takano, Akira, Nakamura, Yuki, Suetsugu, Noriyuki, Kohda, Daisuke, Uyeda, Taro Q P, Wada, Masamitsu
Format: Article
Language:English
Subjects:
Actin Cytoskeleton
Actins
Arabidopsis - genetics
Arabidopsis Proteins - genetics
Chloroplast Proteins - genetics
Chloroplasts - physiology
Light
Movement
Polymerization
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Plants have unique responses to fluctuating light conditions. One such response involves chloroplast photorelocation movement, which optimizes photosynthesis under weak light by the accumulation of chloroplasts along the periclinal side of the cell, which prevents photodamage under strong light by avoiding chloroplast positioning toward the anticlinal side of the cell. This light-responsive chloroplast movement relies on the reorganization of chloroplast actin (cp-actin) filaments. Previous studies have suggested that CHLOROPLAST UNUSUAL POSITIONING 1 (CHUP1) is essential for chloroplast photorelocation movement as a regulator of cp-actin filaments. In this study, we conducted comprehensive analyses to understand CHUP1 function. Functional, fluorescently tagged CHUP1 colocalized with and was coordinately reorganized with cp-actin filaments on the chloroplast outer envelope during chloroplast movement in Arabidopsis thaliana. CHUP1 distribution was reversibly regulated in a blue light- and phototropin-dependent manner. X-ray crystallography revealed that the CHUP1-C-terminal domain shares structural homology with the formin homology 2 (FH2) domain, despite lacking sequence similarity. Furthermore, the CHUP1-C-terminal domain promoted actin polymerization in the presence of profilin in vitro. Taken together, our findings indicate that CHUP1 is a plant-specific actin polymerization factor that has convergently evolved to assemble cp-actin filaments and enables chloroplast photorelocation movement.
ISSN:1040-4651
1532-298X
1532-298X
DOI:10.1093/plcell/koad320