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Updated: Mar 2, 2026
Rapid Isolation of the Mitoribosome from HEK Cells
Published on: October 4, 2018
The DEAD-box helicase Mss116 plays distinct roles in mitochondrial ribogenesis and mRNA-specific translation
Dasmanthie De Silva1, Sarah Poliquin1, Rui Zeng1
1Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
Abstract:
Members of the DEAD-box family are often multifunctional proteins involved in several RNA transactions. Among them, yeast Saccharomyces cerevisiae Mss116 participates in mitochondrial intron splicing and, under cold stress, also in mitochondrial transcription elongation. Here, we show that Mss116 interacts with the mitoribosome assembly factor Mrh4, is required for efficient mitoribosome biogenesis, and consequently, maintenance of the overall mitochondrial protein synthesis rate. Additionally, Mss116 is required for efficient COX1 mRNA translation initiation and elongation. Mss116 interacts with a COX1 mRNA-specific translational activator, the pentatricopeptide repeat protein Pet309. In the absence of Mss116, Pet309 is virtually absent, and although mitoribosome loading onto COX1 mRNA can occur, activation of COX1 mRNA translation is impaired. Mutations abolishing the helicase activity of Mss116 do not prevent the interaction of Mss116 with Pet309 but also do not allow COX1 mRNA translation. We propose that Pet309 acts as an adaptor protein for Mss116 action on the COX1 mRNA 5΄-UTR to promote efficient Cox1 synthesis. Overall, we conclude that the different functions of Mss116 in the biogenesis and functioning of the mitochondrial translation machinery depend on Mss116 interplay with its protein cofactors.
Insights
The DEAD-box protein Mss116 is crucial for yeast mitochondrial protein synthesis by aiding mitoribosome assembly and COX1 mRNA translation, working with Pet309.
Area of Science:
- Mitochondrial biology
- Molecular genetics
- RNA biology
Background:
- DEAD-box proteins are vital for RNA metabolism.
- Mss116 in yeast Saccharomyces cerevisiae has known roles in mitochondrial intron splicing and transcription.
Purpose of the Study:
- To elucidate the role of Mss116 in mitochondrial translation and mitoribosome biogenesis.
- To investigate the interaction of Mss116 with other mitochondrial factors, specifically in COX1 mRNA translation.
Main Methods:
- Co-immunoprecipitation to study protein interactions.
- Analysis of mitoribosome assembly and mitochondrial protein synthesis rates.
- Investigating mRNA translation efficiency via mutations and protein expression levels.
Main Results:
- Mss116 interacts with mitoribosome assembly factor Mrh4, essential for mitoribosome biogenesis and protein synthesis.
- Mss116 is required for COX1 mRNA translation initiation and elongation, interacting with the activator Pet309.
- Mss116's helicase activity is not required for Pet309 interaction but is essential for COX1 mRNA translation.
Conclusions:
- Mss116 is a key factor in maintaining mitochondrial translation by facilitating mitoribosome biogenesis and COX1 mRNA translation.
- Pet309 acts as an adaptor for Mss116 on the COX1 mRNA 5'-UTR, promoting Cox1 synthesis.
- Mss116's diverse functions in mitochondrial translation are mediated through interactions with protein cofactors.
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