Article
- The EMBO Journal (2004) 23, 520 - 530
- doi:10.1038/sj.emboj.7600089
Published online: 5 February 2004
Subject Category:
Preprotein recognition by the Toc complex
Thomas Becker1,a, Marko Jelic1,a, Aleksandar Vojta1, Alfons Radunz2, Jürgen Soll1 and Enrico Schleiff1
- Botanik, LMU München, Menzinger Str. 67, München, Germany
- Department of Biology, University of Bielefeld, Bielefeld, Germany
Correspondence to:
Enrico Schleiff, Botanik, LMU München, Menzinger Str. 67, Room 223, D-80368 München, Germany. Tel.: +49 89 17861 182; Fax: +49 89 17861 185; E-mail: schleiff@botanik.biologie.uni-muenchen.de
aThese authors contributed equally to this work
Received 27 August 2003; Accepted 2 January 2004
Abstract
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.
Keywords:
- preprotein recognition,
- Toc159,
- Toc complex
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