Gene

Cell biology

Biology

18S ribosomal RNA

Protein biosynthesis

Ribosomal protein

Biochemistry

Mitochondrial ribosome

Computational biology

Eukaryotic Ribosome

Ribonucleoprotein

Ribosomal RNA

Mitochondrion

Ribosome

Trypanosoma brucei

Science

Ribosomal RNA (rRNA) plays key functional and architectural roles in ribosomes. Using electron microscopy, we determined the atomic structure of a highly divergent ribosome found in mitochondria of Trypanosoma brucei, a unicellular parasite that causes sleeping sickness in humans. The trypanosomal mitoribosome features the smallest rRNAs and contains more proteins than all known ribosomes. The structure shows how the proteins have taken over the role of architectural scaffold from the rRNA: They form an autonomous outer shell that surrounds the entire particle and stabilizes and positions the functionally important regions of the rRNA. Our results also reveal the "minimal" set of conserved rRNA and protein components shared by all ribosomes that help us define the most essential functional elements.

Evolutionary shift toward protein-based architecture in trypanosomal mitochondrial ribosomes