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Publication Abstract from PubMed

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-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 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.

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 Mol Plant. 2024 Nov 4;17(11):1702-1718. doi: 10.1016/j.molp.2024.09.010. Epub , 2024 Sep 25. PMID:39327731^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.