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Updated: Jun 16, 2026
Mitochondrial Transformation in Baker's Yeast to Study Translation and Respiratory Complex Assembly
Published on: June 7, 2024
Targeting of the cytosolic poly(A) binding protein PABPC1 to mitochondria causes mitochondrial translation inhibition
Mateusz Wydro1, Agnieszka Bobrowicz, Richard J Temperley
1Mitochondrial Research Group, Medical School, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.
Abstract:
Mammalian mitochondria contain their own genome that is almost fully transcribed from both strands, generating polycistronic RNA units that are processed and matured. The mitochondrial mRNA is modified by oligo- or polyadenylation at the 3' termini, but the exact function of this post-transcriptional addition is unclear. Current debate focuses on the role of polyadenylation in transcript stability. An equally likely function that has received little attention is that, as in the cytosol of eukaryotes, polyadenylation facilitates translation in the mitochondrion. To address this issue, we have targeted cytosolic proteins to the mitochondrion, a poly(A) specific 3' exoribonuclease, mtPARN, and a poly(A)binding protein, mtPABP1. Removal of the 3' adenylyl extensions had a variable effect on mt-mRNA steady-state levels, increasing (MTND1, 2, 5) or decreasing (MTCO1, 2, RNA14) certain species with minimal effect on others (RNA7, MTND3). Translation was markedly affected, but interpretation of this was complicated by the concomitant 3' truncation of the open reading frame in most cases. Coating of the poly(A) tail by mtPABP1, however, did not lead to transcript decay but caused a marked inhibition of mitochondrial translation. These data are consistent with endogenous RNA-binding factor(s) interacting with the poly(A) to optimize mitochondrial protein synthesis.
Insights
Mitochondrial mRNA polyadenylation
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Mammalian mitochondria possess their own genome, transcribed into polycistronic RNA units.
- Mitochondrial messenger RNA (mRNA) undergoes 3' end modification via oligo- or polyadenylation.
- The precise function of mitochondrial mRNA polyadenylation, particularly in translation, remains largely unexplored.
Purpose of the Study:
- To investigate the role of 3' polyadenylation in mitochondrial mRNA stability and translation.
- To determine if polyadenylation acts as a translational enhancer in mitochondria, similar to the cytosol.
- To elucidate the function of mitochondrial poly(A)-binding proteins in mRNA metabolism.
Main Methods:
- Targeting of cytosolic poly(A)-specific 3' exoribonuclease (mtPARN) and poly(A)-binding protein (mtPABP1) to mammalian mitochondria.
- Analysis of mitochondrial mRNA levels and translation efficiency following manipulation of 3' polyadenylation.
- Assessing the impact of mtPABP1 binding to poly(A) tails on transcript stability and protein synthesis.
Main Results:
- Removal of 3' adenylyl extensions had variable effects on mitochondrial mRNA stability, increasing some and decreasing others.
- Mitochondrial translation was significantly affected by polyadenylation status, though open reading frame truncation complicated direct interpretation.
- Binding of mtPABP1 to poly(A) tails inhibited mitochondrial translation without causing transcript decay.
Conclusions:
- Mitochondrial mRNA polyadenylation plays a crucial role in regulating mitochondrial protein synthesis.
- Polyadenylation may facilitate translation in mitochondria, analogous to its role in the cytosol.
- Endogenous RNA-binding factors likely interact with mitochondrial poly(A) tails to optimize protein synthesis.
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