Mutant MRPS5 affects mitoribosomal accuracy and confers stress-related behavioral alterations.

Rashid Akbergenov,Jochen Schacht,Stefan Duscha,Anne Eckert,Heithem Boukari,Reda Juskeviciene,Stephan Frank,Pietro Freihofer,Youjin Teo,Dimitri Shcherbakov,Karen Schmitt,Hubert Rehrauer,Naoki Oishi,Björn Oettinghaus,Kader Thiam,Ann Kristina Fritz ,Patricia Isnard-Petit ,David P Wolfer ,Éric Westhof ,Erik C Böttger

doi:10.15252/embr.201846193

Abstract

The 1555 A to G substitution in mitochondrial 12S A‐site rRNA is associated with maternally transmitted deafness of variable penetrance in the absence of otherwise overt disease. Here, we recapitulate the suggested A1555G‐mediated pathomechanism in an experimental model of mitoribosomal mistranslation by directed mutagenesis of mitoribosomal protein MRPS5. We first establish that the ratio of cysteine/methionine incorporation and read‐through of mtDNA‐encoded MT‐CO1 protein constitute reliable measures of mitoribosomal misreading. Next, we demonstrate that human HEK293 cells expressing mutant V336Y MRPS5 show increased mitoribosomal mistranslation. As for immortalized lymphocytes of individuals with the pathogenic A1555G mutation, we find little changes in the transcriptome of mutant V336Y MRPS5 HEK cells, except for a coordinated upregulation of transcripts for cytoplasmic ribosomal proteins. Homozygous knock‐in mutant Mrps5 V338Y mice show impaired mitochondrial function and a phenotype composed of enhanced susceptibility to noise‐induced hearing damage and anxiety‐related behavioral alterations. The experimental data in V338Y mutant mice point to a key role of mitochondrial translation and function in stress‐related behavioral and physiological adaptations.

Highlights

The 1555 A to G substitution in mitochondrial 12S A-site rRNA is associated with maternally transmitted deafness of variable penetrance in the absence of otherwise overt disease
Modeling indicates that replacement of the corresponding native amino acid with the large aromatic tyrosine residue in both mitochondrial MRPS5 and bacterial RpsE (Escherichia coli rpsE A127Y) would result in steric hindrance within the protein Cterminal domain, similar to what is observed for S200Y in the yeast Rps2 protein (Appendix Fig S1)
Following the in silico identification of a putative ram mutation in mammalian MRPS5, phylogenetic reconstructions provided evidence that the corresponding mutation A127Y in homologous bacterial ribosomal protein rpsE (E. coli) results in mistranslation as evidenced by increased incorporation of nearcognate aa-tRNA species and stop codon read-through

Summary

Introduction

The 1555 A to G substitution in mitochondrial 12S A-site rRNA is associated with maternally transmitted deafness of variable penetrance in the absence of otherwise overt disease. We recapitulate the suggested A1555G-mediated pathomechanism in an experimental model of mitoribosomal mistranslation by directed mutagenesis of mitoribosomal protein MRPS5. We first establish that the ratio of cysteine/methionine incorporation and readthrough of mtDNA-encoded MT-CO1 protein constitute reliable measures of mitoribosomal misreading. We demonstrate that human HEK293 cells expressing mutant V336Y MRPS5 show increased mitoribosomal mistranslation. As for immortalized lymphocytes of individuals with the pathogenic A1555G mutation, we find little changes in the transcriptome of mutant V336Y MRPS5 HEK cells, except for a coordinated upregulation of transcripts for cytoplasmic ribosomal proteins. Homozygous knock-in mutant Mrps V338Y mice show impaired mitochondrial function and a phenotype composed of enhanced susceptibility to noise-induced hearing damage and anxiety-related behavioral alterations. The experimental data in V338Y mutant mice point to a key role of mitochondrial translation and function in stress-related behavioral and physiological adaptations

Methods

Results

Conclusion