Architecture of the ATP-driven motor for protein import into chloroplasts

Ning Wang; Jiale Xing; Xiaodong Su; Junting Pan; Hui Chen; Lifang Shi; Long Si; Wenqiang Yang; Mei Li

doi:10.1016/j.molp.2024.09.010

Architecture of the ATP-driven motor for protein import into chloroplasts

Mol Plant. 2024 Nov 4;17(11):1702-1718. doi: 10.1016/j.molp.2024.09.010. Epub 2024 Sep 25.

Authors

Ning Wang¹, Jiale Xing², Xiaodong Su³, Junting Pan⁴, Hui Chen⁵, Lifang Shi¹, Long Si³, Wenqiang Yang⁶, Mei Li⁷

Affiliations

¹ Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
² Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
³ Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing, China.
⁴ Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing, China; China National Botanical Garden, Beijing 100093, China; Institute of Botany, Chinese Academy of Sciences, Beijing, China.
⁵ Key Laboratory of Epigenetic Regulation and Intervention, Chinese Academy of Sciences Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.
⁶ Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing, China; China National Botanical Garden, Beijing 100093, China; Institute of Botany, Chinese Academy of Sciences, Beijing, China. Electronic address: [email protected].
⁷ Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China. Electronic address: [email protected].

PMID: 39327731
DOI: 10.1016/j.molp.2024.09.010

Abstract

Thousands of nuclear-encoded proteins are transported into chloroplasts through the TOC-TIC translocon that spans the chloroplast envelope membranes. A motor complex pulls the translocated proteins out of the TOC-TIC complex into the chloroplast stroma by hydrolyzing ATP. The Orf2971-FtsHi complex has been suggested to serve as the ATP-hydrolyzing motor in Chlamydomonas reinhardtii, but little is known about its architecture and assembly. Here, we report the 3.2-Å resolution structure of the Chlamydomonas Orf2971-FtsHi complex. The 20-subunit complex spans the chloroplast inner envelope, with two bulky modules protruding into the intermembrane space and stromal matrix. Six subunits form a hetero-hexamer that potentially provides the pulling force through ATP hydrolysis. The remaining subunits, including potential enzymes/chaperones, likely facilitate the complex assembly and regulate its proper function. Taken together, our results provide the structural foundation for a mechanistic understanding of chloroplast protein translocation.

Keywords: ATP-driven motor; Chlamydomonas; Orf2971–FtsHi; chloroplast protein translocation; cryo-EM structure.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adenosine Triphosphate* / metabolism
Chlamydomonas reinhardtii* / metabolism
Chloroplasts* / metabolism
Plant Proteins / chemistry
Plant Proteins / metabolism
Protein Transport*

Substances

Adenosine Triphosphate
Plant Proteins