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| Title | Numerous rRNA molecules form the apicomplexan mitoribosome via repurposed protein and RNA elements. |
|---|---|
| Journal, issue, pages | Nat Commun, Vol. 16, Issue 1, Page 817, Year 2025 |
| Publish date | Jan 18, 2025 |
Authors | Shikha Shikha / Victor Tobiasson / Mariana Ferreira Silva / Jana Ovciarikova / Dario Beraldi / Alexander Mühleip / Lilach Sheiner / ![]() |
| PubMed Abstract | Mitochondrial ribosomes (mitoribosomes) are essential, and their function of synthesising mitochondrial proteins is universal. The core of almost all mitoribosomes is formed from a small number of ...Mitochondrial ribosomes (mitoribosomes) are essential, and their function of synthesising mitochondrial proteins is universal. The core of almost all mitoribosomes is formed from a small number of long and self-folding rRNA molecules. In contrast, the mitoribosome of the apicomplexan parasite Toxoplasma gondii assembles from over 50 extremely short rRNA molecules. Here, we use cryo-EM to discover the features that enable this unusual mitoribosome to perform its function. We reveal that poly-A tails added to rRNA molecules are integrated into the ribosome, and we demonstrate their essentiality for mitoribosome formation and for parasite survival. This is a distinct function for poly-A tails, which are otherwise known primarily as stabilisers of messenger RNAs. Furthermore, while ribosomes typically consist of unique rRNA sequences, here nine sequences are used twice, each copy integrated in a different mitoribosome domain, revealing one of the mechanisms enabling the extreme mitochondrial genome reduction characteristic to Apicomplexa and to a large group of related microbial eukaryotes. Finally, several transcription factor-like proteins are repurposed to compensate for reduced or lost critical ribosomal domains, including members of the ApiAP2 family thus far considered to be DNA-binding transcription factors. |
External links | Nat Commun / PubMed:39827269 / PubMed Central |
| Methods | EM (single particle) |
| Resolution | 2.2 - 2.52 Å |
| Structure data | EMDB-52348, PDB-9hqv: EMDB-52551, PDB-9i05: |
| Chemicals | ![]() ChemComp-ATP: ![]() ChemComp-MG: ![]() ChemComp-ZN: ![]() ChemComp-FES: |
| Source |
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Keywords | RIBOSOME / Toxoplasma gondii / parasite / mitochondrial ribosome / SSU / large subunit / LSU |
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