9HQV
Cryo-EM structure of the small subunit of the mitochondrial ribosome from Toxoplasma gondii
This is a non-PDB format compatible entry.
Summary for 9HQV
| Entry DOI | 10.2210/pdb9hqv/pdb |
| EMDB information | 52348 |
| Descriptor | Enoyl-CoA hydratase/isomerase family protein, uS10m, Putative ribosomal protein S11, ... (90 entities in total) |
| Functional Keywords | toxoplasma gondii, parasite, mitochondrial ribosome, ssu, large subunit, ribosome |
| Biological source | Toxoplasma gondii More |
| Total number of polymer chains | 88 |
| Total formula weight | 2927672.02 |
| Authors | |
| Primary citation | Shikha, S.,Tobiasson, V.,Ferreira Silva, M.,Ovciarikova, J.,Beraldi, D.,Muhleip, A.,Sheiner, L. Numerous rRNA molecules form the apicomplexan mitoribosome via repurposed protein and RNA elements. Nat Commun, 16:817-817, 2025 Cited by 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 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. PubMed: 39827269DOI: 10.1038/s41467-025-56057-9 PDB entries with the same primary citation |
| Experimental method | ELECTRON MICROSCOPY (2.52 Å) |
Structure validation
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