These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: A substrate-independent, 14:3:3 protein-mediated plastid import pathway of NADPH:protochlorophyllide oxidoreductase A.
    Author: Schemenewitz A, Pollmann S, Reinbothe C, Reinbothe S.
    Journal: Proc Natl Acad Sci U S A; 2007 May 15; 104(20):8538-43. PubMed ID: 17483469.
    Abstract:
    Plastids are semiautonomous organelles that contain only limited coding information in their own DNA. Because most of their genome was transferred to the nucleus after their endosymbiotic origin, plastids must import the major part of their protein constituents from the cytosol. The exact role of cytosolic targeting factors in the regulation of plastid protein import has not been determined. Here, we report that the nucleus-encoded NADPH:protochlorophyllide (Pchlide) oxidoreductase A plastid precursor (pPORA) can use two different plastid import pathways that differ by the requirements for cytosolic 14:3:3 proteins and Hsp70. pPORA synthesized in a wheat germ lysate segregated into different precursor fractions. While import of free pPORA and only Hsp70-complexed pPORA was Pchlide-dependent and involved the previously identified Pchlide-dependent translocon, 14:3:3 protein- and Hsp70-complexed pPORA was transported into Pchlide-free chloroplasts through the Toc75-containing standard translocon at the outer chloroplast membrane/translocon at the inner chloroplast membrane machinery. A 14:3:3 protein binding site was identified in the mature region of the (35)S-pPORA, which governed 14:3:3 protein- and Hsp70-mediated, Pchlide-independent plastid import. Collectively, our results reveal that the import of pPORA into the plastids is tightly regulated and involves different cytosolic targeting factors and plastid envelope translocon complexes.
    [Abstract] [Full Text] [Related] [New Search]