Phenotype of Mrps5-associated polymorphisms is intimately linked to mitoribosomal misreading

Recently, we have identified a point mutation V338Y in mammalian nuclear-encoded mitochondrial protein MrpS5 that confers error-prone mitochondrial protein synthesis. In-vivo, mutation V338Y was associated with a distinct phenotype including impaired mitochondrial function, enhanced susceptibility to noise-induced hearing damage, anxiety-related behavioral alterations, and age-associated metabolic changes in muscle. To challenge the link between V338Y-mediated misreading and in-vivo phenotype, we introduced mutation G315R into the MRPS5 gene; MRPS5 G315R is homologous to the established bacterial ram mutation uS5 G104R. In contrast to the phylogenetically closely related bacterial translation, the corresponding MRPS5 G315R mutation did not affect the accuracy of mitochondrial protein synthesis. In addition, in the absence of mitochondrial misreading, homozygous mutant MRPS5G315R/G315R mice did not show phenotype distinct from wild-type animals. Transcriptomic profile of total RNA extracted from HEK cells stably transfected with MRPS5 WT or mutant