Format

Send to

Choose Destination
Elife. 2017 Aug 31;6. pii: e28324. doi: 10.7554/eLife.28324.

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

Author information

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.

KEYWORDS:

S. cerevisiae; Tim23; biochemistry; biophysics; electrophysiology; membrane channels; mitochondria; mitochondrial biogenesis; protein trafficking; structural biology

PMID:
28857742
PMCID:
PMC5578737
DOI:
10.7554/eLife.28324
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for eLife Sciences Publications, Ltd Icon for PubMed Central
Loading ...
Support Center