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bioRxiv · 10.1101/2024.09.02.610899

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

wang, n.·Xing, J.·Su, X.·Pan, J.·Chen, H.·Shi, L.·Si, L.·Yang, W.·Li, M.
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Abstract

Thousands of nuclear-encoded proteins are transported into chloroplasts through the TOC-TIC translocon spanning 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 was 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-[A] 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 potentially providing the pulling force through ATP hydrolysis. The remaining subunits, including potential enzymes/chaperones, likely facilitate the complex assembly and regulate its proper function. Our results provide the structural foundation for mechanistic understanding of chloroplast protein translocation.

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wang, n., Xing, J., Su, X., Pan, J., Chen, H., Shi, L., Si, L., Yang, W., Li, M.. 2024-09-03. Architecture of the ATP-driven motor for protein import into chloroplasts. https://doi.org/10.1101/2024.09.02.610899

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