Cation selectivity of the presequence translocase channel Tim23 is crucial for efficient protein import

Author:

Denkert Niels1ORCID,Schendzielorz Alexander Benjamin1ORCID,Barbot Mariam1,Versemann Lennart1,Richter Frank1,Rehling Peter123ORCID,Meinecke Michael134ORCID

Affiliation:

1. Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany

2. Max Planck Institute for Biophysical Chemistry, Göttingen, Germany

3. Göttinger Zentrum für Molekulare Biowissenschaften, Göttingen, Germany

4. European Neuroscience Institute Göttingen, Göttingen, Germany

Abstract

Virtually all mitochondrial matrix proteins and a considerable number of inner membrane proteins carry a positively charged, N-terminal presequence and are imported by the TIM23 complex (presequence translocase) located in the inner mitochondrial membrane. The voltage-regulated Tim23 channel constitutes the actual protein-import pore wide enough to allow the passage of polypeptides with a secondary structure. In this study, we identify amino acids important for the cation selectivity of Tim23. Structure based mutants show that selectivity is provided by highly conserved, pore-lining amino acids. Mutations of these amino acid residues lead to reduced selectivity properties, reduced protein import capacity and they render the Tim23 channel insensitive to substrates. We thus show that the cation selectivity of the Tim23 channel is a key feature for substrate recognition and efficient protein import.

Funder

Deutsche Forschungsgemeinschaft

Publisher

eLife Sciences Publications, Ltd

Subject

General Immunology and Microbiology,General Biochemistry, Genetics and Molecular Biology,General Medicine,General Neuroscience

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