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Preprotein recognition by the Toc complex
Author(s) -
Becker Thomas,
Jelic Marko,
Vojta Aleksandar,
Radunz Alfons,
Soll Jürgen,
Schleiff Enrico
Publication year - 2004
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600089
Subject(s) - biology , computational biology , microbiology and biotechnology
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.