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Cells 2018, 7(10), 172; https://doi.org/10.3390/cells7100172

Insertion Defects of Mitochondrially Encoded Proteins Burden the Mitochondrial Quality Control System

Department of Biochemistry and Biophysics, Stockholm University, SE-10691 Stockholm, Sweden
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Received: 14 September 2018 / Revised: 7 October 2018 / Accepted: 16 October 2018 / Published: 17 October 2018
(This article belongs to the Special Issue Cellular Stress Response in Health and Disease)
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Abstract

The mitochondrial proteome contains proteins from two different genetic systems. Proteins are either synthesized in the cytosol and imported into the different compartments of the organelle or directly produced in the mitochondrial matrix. To ensure proteostasis, proteins are monitored by the mitochondrial quality control system, which will degrade non-native polypeptides. Defective mitochondrial membrane proteins are degraded by membrane-bound AAA-proteases. These proteases are regulated by factors promoting protein turnover or preventing their degradation. Here we determined genetic interactions between the mitoribosome receptors Mrx15 and Mba1 with the quality control system. We show that simultaneous absence of Mrx15 and the regulators of the i-AAA protease Mgr1 and Mgr3 provokes respiratory deficiency. Surprisingly, mutants lacking Mrx15 were more tolerant against proteotoxic stress. Furthermore, yeast cells became hypersensitive against proteotoxic stress upon deletion of MBA1. Contrary to Mrx15, Mba1 cooperates with the regulators of the m-AAA and i-AAA proteases. Taken together, these results suggest that membrane protein insertion and mitochondrial AAA-proteases are functionally coupled, possibly reflecting an early quality control step during mitochondrial protein synthesis. View Full-Text
Keywords: mitochondria; mitochondrial quality control; membrane protein insertion; membrane-bound AAA proteases mitochondria; mitochondrial quality control; membrane protein insertion; membrane-bound AAA proteases
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Vargas Möller-Hergt, B.; Carlström, A.; Suhm, T.; Ott, M. Insertion Defects of Mitochondrially Encoded Proteins Burden the Mitochondrial Quality Control System. Cells 2018, 7, 172.

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