Abstract
Mitochondrial translation in the parasitic protozoan Trypanosoma brucei relies on imported eukaryotic-type tRNAs as well as on bacterial-type ribosomes that have the shortest known rRNAs. Here we have identified the mitochondrial translation elongation factors EF-Tu, EF-Ts, EF-G1 and release factor RF1 of trypanosomatids and show that their ablation impairs growth and oxidative phosphorylation. In vivo labelling experiments and a SILAC-based analysis of the global proteomic changes induced by EF-Tu RNAi directly link EF-Tu to mitochondrial translation. Moreover, EF-Tu RNAi reveals downregulation of many nuclear encoded subunits of cytochrome oxidase as well as of components of the bc1-complex, whereas most cytosolic ribosomal proteins were upregulated. Interestingly, T.\,brucei\>EF-Tu has a 30-amino-acid-long, highly charged subdomain, which is unique to trypanosomatids. A combination of RNAi and complementation experiments shows that this subdomain is essential for EF-Tu function, but that it can be replaced by a similar sequence found in eukaryotic EF-1a, the cytosolic counterpart of EF-Tu. A recent cryo-electron microscopy study revealed that trypanosomatid mitochondrial ribosomes have a unique intersubunit space that likely harbours the EF-Tu binding site. These findings suggest that the trypanosomatid-specific EF-Tu subdomain serves as an adaption for binding to these unusual mitochondrial ribosomes.
- &
- *amino
- acid
- alignment,to_read,trypanosoma
- brucei
- brucei/genetics/growth
- complex
- data,mutation,oxidative
- development/*metabolism
- elongation
- expression
- factor
- factors/genetics/metabolism,peptide
- factors/genetics/metabolism,proteomics,protozoan
- g/genetics/metabolism,peptide
- interference,sequence
- iv/metabolism,gene
- line,electron
- motifs,amino
- phosphorylation,peptide
- proteins/*chemistry/genetics/physiology,ribosomes/*metabolism,rna
- proteins/*chemistry/physiology,molecular
- regulation,mitochondria/genetics/*metabolism,mitochondrial
- sequence
- sequence,cell
- termination
- transport
- tu/*chemistry/genetics/physiology,peptide
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