Two kinesin-like proteins mediate actin-based chloroplast movement in Arabidopsis thaliana

Noriyuki Suetsugu, Noboru Yamada, Takatoshi Kagawa, Hisashi Yonekura, Taro Q.P. Uyedad, Akeo Kadota, Masamitsu Wada

Research output: Contribution to journalArticle

114 Citations (Scopus)

Abstract

Organelle movement is essential for efficient cellular function in eukaryotes. Chloroplast photorelocation movement is important for plant survival as well as for efficient photosynthesis. Chloroplast movement generally is actin dependent and mediated by blue light receptor phototropins. In Arabidopsis thaliana, phototropins mediate chloroplast movement by regulating short actin filaments on chloroplasts (cp-actin filaments), and the chloroplast outer envelope protein CHUP1 is necessary for cp-actin filament accumulation. However, other factors involved in cp-actin filament regulation during chloroplast movement remain to be determined. Here, we report that two kinesin-like proteins, KAC1 and KAC2, are essential for chloroplasts to move and anchor to the plasma membrane. A kac1 mutant showed severely impaired chloroplast accumulation and slow avoidance movement. A kac1kac2 double mutant completely lacked chloroplast photorelocation movement and showed detachment of chloroplasts from the plasma membrane. KAC motor domains are similar to those of the kinesin-14 subfamily (such as Ncd and Kar3) but do not have detectable microtubule-binding activity. The C-terminal domain of KAC1 could interact with F-actin in vitro. Instead of regulating microtubules, KAC proteins mediate chloroplast movement via cp-actin filaments. We conclude that plants have evolved a unique mechanism to regulate actin-based organelle movement using kinesin-like proteins.

Original languageEnglish
Pages (from-to)8860-8865
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume107
Issue number19
DOIs
Publication statusPublished - 2010 May 11
Externally publishedYes

Keywords

  • Blue light
  • Cp-actin
  • Organelle movement
  • Phototropin

ASJC Scopus subject areas

  • General

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