Mitochondrial Translation Efficiency Controls Cytoplasmic Protein Homeostasis

https://www.sciencedirect.com/science/article/pii/S1550413118302547?via%3Dihub

Suhm T, Kaimal JM, Dawitz H, Peselj C, Masser AE, Hanzén S, Ambrožič M, Smialowska A, Björck ML, Brzezinski P, Nyström T, Büttner S, Andréasson C, Ott M

• As mitochondria possess their own DNA, they also possess their own transcription and translation machinery. 
• This study focuses on the mitochondrial translation machinery. There exists a tradeoff between the accuracy with which mRNAs are translated into protein, and the speed at which proteins can be formed.
• The mitoribosome is structurally similar to the bacterial ribosome. Several mutations are known for the bacterial ribosome which can increase or decrease the fidelity of translation. The authors sought to determine the effects of such mutations in yeast. 
• The authors investigated two mutations in particular: P50R which caused reduced fidelity of translation, and K71T which increased fidelity (likely at the cost of slower translation). Both mutants caused growth defects on galactose (a respiratory substrate which forces oxidative phosphorylation). 
• The authors observed that the K71T hyperaccurate mutant displayed extended lifespan. These mutants also had lower levels of reactive oxygen species and fewer protein aggregates. The authors suggest that hyperaccurate translation inside mitochondria mitigates ROS-induced aggregation of proteins.