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Biochim Biophys Acta. 2015 Aug;1853(8):1850-9. doi: 10.1016/j.bbamcr.2015.04.021. Epub 2015 May 7.

A presequence-binding groove in Tom70 supports import of Mdl1 into mitochondria.

Author information

1
Institute of Cellular Biochemistry, University Medical Center Göttingen, Germany.
2
Department of Molecular Biology, University Medical Center Göttingen, Germany.
3
Department of Molecular Structural Biology, University of Göttingen, Germany.
4
Proteomics Group, Max Planck Institute of Experimental Medicine, Göttingen, Germany.
5
Institute of Cellular Biochemistry, University Medical Center Göttingen, Germany; Max Planck Institute for Biophysical Chemistry, Göttingen, Germany. Electronic address: Peter.Rehling@medizin.uni-goettingen.de.

Abstract

The translocase of the outer mitochondrial membrane (TOM complex) is the general entry gate into mitochondria for almost all imported proteins. A variety of specific receptors allow the TOM complex to recognize targeting signals of various precursor proteins that are transported along different import pathways. Aside from the well-characterized presequence receptors Tom20 and Tom22 a third TOM receptor, Tom70, binds proteins of the carrier family containing multiple transmembrane segments. Here we demonstrate that Tom70 directly binds to presequence peptides using a dedicated groove. A single point mutation in the cavity of this pocket (M551R) reduces the presequence binding affinity of Tom70 ten-fold and selectively impairs import of the presequence-containing precursor Mdl1 but not the ADP/ATP carrier (AAC). Hence Tom70 contributes to the presequence import pathway by recognition of the targeting signal of the Mdl1 precursor.

KEYWORDS:

Mitochondria; Presequence; Protein import; Tom70

PMID:
25958336
DOI:
10.1016/j.bbamcr.2015.04.021
[Indexed for MEDLINE]
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