Scientists map the cellular machinery that powers mitochondrial energy production
Researchers have decoded how two proteins ferry genetic instructions to the mitochondria's protein-making factories, revealing the mechanism cells use to regulate energy production. The discovery could unlock new therapeutic targets for genetic diseases and age-related conditions tied to mitochondrial dysfunction, opening possibilities for treatments affecting millions of patients.
Originaltitel: Structural basis of LRPPRC–SLIRP-dependent translation by the mitoribosome
<p>In mammalian mitochondria, mRNAs are cotranscriptionally stabilized by the protein factor LRPPRC (leucine-rich pentatricopeptide repeat-containing protein). Here, we characterize LRPPRC as an mRNA delivery factor and report its cryo-electron microscopy structure in complex with SLIRP (SRA stem-loop-interacting RNA-binding protein), mRNA and the mitoribosome. The structure shows that LRPPRC associates with the mitoribosomal proteins mS39 and the N terminus of mS31 through recognition of the LRPPRC helical repeats. Together, the proteins form a corridor for handoff of the mRNA. The mRNA is directly bound to SLIRP, which also has a stabilizing function for LRPPRC. To delineate the effect of LRPPRC on individual mitochondrial transcripts, we used RNA sequencing, metabolic labeling and mitoribosome profiling, which showed a transcript-specific influence on mRNA translation efficiency, with cytochrome c oxidase subunit 1 and 2 translation being the most affected. Our data suggest that LRPPRC–SLIRP acts in recruitment of mitochondrial mRNAs to modulate their translation. Collectively, the data define LRPPRC–SLIRP as a regulator of the mitochondrial gene expression system.</p>