Preprotein recognition by the Toc complex

The Toc core complex consists of the pore‐forming Toc75 and the GTPases Toc159 and Toc34. We confirm that the receptor form of Toc159 is integrated into the membrane. The association of Toc34 to Toc75/Toc159 is GTP dependent and enhanced by preprotein interaction. The N‐terminal half of the pSSU tra...

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Bibliographic Details
Published in:The EMBO journal 2004-02, Vol.23 (3), p.520-530
Main Authors: Becker, Thomas, Jelic, Marko, Vojta, Aleksandar, Radunz, Alfons, Soll, Jürgen, Schleiff, Enrico
Format: Article
Language:English
Subjects:
Arabidopsis - chemistry
Arabidopsis - physiology
Arabidopsis Proteins - chemistry
Arabidopsis Proteins - metabolism
Chloroplasts - chemistry
Chloroplasts - metabolism
Chloroplasts - ultrastructure
EMBO30
GTP Phosphohydrolases - chemistry
GTP Phosphohydrolases - metabolism
Hydrolysis
Intracellular Membranes - chemistry
Intracellular Membranes - metabolism
Intracellular Membranes - ultrastructure
Membrane Proteins - chemistry
Membrane Proteins - metabolism
Membranes, Artificial
Multiprotein Complexes - chemistry
Multiprotein Complexes - metabolism
Peptides - chemistry
Peptides - metabolism
Plant Leaves - chemistry
Plant Leaves - metabolism
Plant Leaves - ultrastructure
preprotein recognition
Protein Binding
Protein Precursors - chemistry
Protein Precursors - metabolism
Protein Transport - physiology
Toc complex
Toc159
Translocation
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Summary:The Toc core complex consists of the pore‐forming Toc75 and the GTPases Toc159 and Toc34. We confirm that the receptor form of Toc159 is integrated into the membrane. The association of Toc34 to Toc75/Toc159 is GTP dependent and enhanced by preprotein interaction. The N‐terminal half of the pSSU transit peptide interacts with high affinity with Toc159, whereas the C‐terminal part stimulates its GTP hydrolysis. The phosphorylated C‐terminal peptide of pSSU interacts strongly with Toc34 and therefore inhibits binding and translocation of pSSU into Toc proteoliposomes. In contrast, Toc159 recognises only the dephosphorylated forms. The N‐terminal part of the pSSU presequence does not influence binding to the Toc complex, but is able to block import into proteoliposomes through its interaction with Toc159. We developed a model of differential presequence recognition by Toc34 and Toc159.
ISSN:0261-4189
1460-2075
DOI:10.1038/sj.emboj.7600089