The plastid-encoded protein Orf2971 is required for protein translocation and chloroplast quality control.

Abstract

Photosynthesis and the biosynthesis of many important metabolites occur in chloroplasts. In these semi-autonomous organelles, the chloroplast genome encodes approximately 100 proteins. The remaining chloroplast proteins, close to 3,000, are encoded by nuclear genes whose products are translated in the cytosol and imported into chloroplasts. However, there is still no consensus on the composition of the protein import machinery including its motor proteins and on how newly imported chloroplast proteins are refolded. In this study, we have examined the function of orf2971, the largest chloroplast gene of Chlamydomonas reinhardtii. The depletion of Orf2971 causes the accumulation of protein precursors, partial proteolysis and aggregation of proteins, increased expression of chaperones and proteases, and autophagy. Orf2971 interacts with the TIC (translocon at the inner chloroplast envelope) complex, catalyzes ATP (adenosine triphosphate) hydrolysis, and associates with chaperones and chaperonins. We propose that Orf2971 is intimately connected to the protein import machinery and plays an important role in chloroplast protein quality control.

• Authors: Jiale Xing, Junting Pan, Heng Yi, Kang Lv, Qiuliang Gan, Meimei Wang, Haitao Ge, Xiahe Huang, Fang Huang, Yingchun Wang, Jean-David Rochaix, Wenqiang Yang
• Journal: The Plant cell (Plant Cell) Vol. 34 Issue 9 Pg. 3383-3399 (08 25 2022) ISSN: 1532-298X [Electronic] England
• PMID: 35708659 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © The Author(s) 2022. Published by Oxford University Press on behalf of American Society of Plant Biologists.

Chemical References

• Chloroplast Proteins
• Molecular Chaperones
• Plant Proteins

Topics

• Cell Nucleus
• Chloroplast Proteins
• Chloroplasts
• Molecular Chaperones
• Plant Proteins
• Protein Transport