Peroxisomal targeting of a protein phosphatase type 2C via mitochondrial transit

Thorsten Stehlik,Jörg Kahnt,Johannes Freitag,Marco Kremp,Michael Bölker

doi:10.1038/s41467-020-16146-3

Abstract

Correct intracellular distribution of proteins is critical for the function of eukaryotic cells. Certain proteins are targeted to more than one cellular compartment, e.g. to mitochondria and peroxisomes. The protein phosphatase Ptc5 from Saccharomyces cerevisiae contains an N-terminal mitochondrial presequence followed by a transmembrane domain, and has been detected in the mitochondrial intermembrane space. Here we show mitochondrial transit of Ptc5 to peroxisomes. Translocation of Ptc5 to peroxisomes depended both on the C-terminal peroxisomal targeting signal (PTS1) and N-terminal cleavage by the mitochondrial inner membrane peptidase complex. Indirect targeting of Ptc5 to peroxisomes prevented deleterious effects of its phosphatase activity in the cytosol. Sorting of Ptc5 involves simultaneous interaction with import machineries of both organelles. We identify additional mitochondrial proteins with PTS1, which localize in both organelles and can increase their physical association. Thus, a tug-of-war-like mechanism can influence the interaction and communication of two cellular compartments.

Highlights

Correct intracellular distribution of proteins is critical for the function of eukaryotic cells
peroxisomal targeting signal type 1 (PTS1) is usually used as a signal for the import of soluble proteins into peroxisomes[1], the type 2 C protein phosphatase Ptc[5] contains both a functional PTS14 and a transmembrane domain
Ptc5-RFP-PTS was expressed in strains either containing the mitochondrial inner membrane protein Tim[50] fused to yellow fluorescent protein (YFP), or the peroxisomal ATP transport protein Ant[1] fused to YFP

Summary

Introduction

Correct intracellular distribution of proteins is critical for the function of eukaryotic cells. Certain proteins are targeted to more than one cellular compartment, e.g. to mitochondria and peroxisomes. Translocation of Ptc[5] to peroxisomes depended both on the C-terminal peroxisomal targeting signal (PTS1) and N-terminal cleavage by the mitochondrial inner membrane peptidase complex. The majority of peroxisomal matrix proteins contains a C-terminal extension known as peroxisomal targeting signal type 1 (PTS1), which is recognized by the cytosolic receptor Pex[54,5]. The protein phosphatase Ptc[5] is sorted to mitochondria and processed in the inner mitochondrial membrane before translocation to the peroxisomal matrix. This mechanism resembles a tug-of-war-like scenario and can influence the association of mitochondria and peroxisomes.

Methods

Results

Conclusion