Structural basis of LRPPRC-SLIRP-dependent translation by the mitoribosome.
Singh, V., Moran, J.C., Itoh, Y., Soto, I.C., Fontanesi, F., Couvillion, M., Huynen, M.A., Churchman, L.S., Barrientos, A., Amunts, A.(2024) Nat Struct Mol Biol 
- PubMed: 39134711 
- DOI: https://doi.org/10.1038/s41594-024-01365-9
- Primary Citation of Related Structures:  
8ANY - PubMed Abstract: 
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 cyclooxygenase 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.
Organizational Affiliation: 
Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden.