MTO1 worked as a modifier in the aminoglycosides sensitivity of yeast carrying a mitochondrial 15S rRNA C1477G mutation.

Xiaoyu Zhu,Qingfeng Yan,Xiangyu He,Wei Wang,Yu Dai,Xufen Zhu,Zhe Yu,Qiyin Zhou,Dan Mishmar

doi:10.1371/journal.pone.0124200

Abstract

MTO1, together with MSS1 and MTO2, is a gene involved in the pathway of encoding a mitochondria-specific RNA-modifying enzyme related to the post-transcriptional modification of mitochondrial tRNAs. We have previously shown that a mutation of the MTO2 or MSS1 gene can suppress the neomycin-sensitive phenotype of yeast carrying a mitochondrial 15S rRNA C1477G mutation. Here we report that a null mutation of MTO1 also can inhibit the aminoglycoside-sensitivity of yeast carrying mitochondrial 15S rRNA C1477G mutation. The C1477G mutation corresponds to the human 12S rRNA A1555G mutation. Yeast with an mtDNA C1477G mutation exhibits hypersensitivity to neomycin and displays mitochondrial function impairment beyond neomycin treatment. When the mto1 null mutation and mitochondrial C1477G mutation coexist, the yeast strain shows growth recovery. The deletion of the nuclear gene MTO1 regulates neomycin sensitivity in yeast carrying the mitochondrial 15S rRNA C1477G mutation. MTO1 deletion causes the expression levels of the key glycolytic genes HXK2, PFK1 and PYK1 to become significantly up-regulated. The energy deficit due to impaired mitochondrial function was partially compensated by the energy generated by glycolysis. Being in the same pathway, the regulation of MTO1, MSS1 and MTO2 to the neomycin-sensitivity of yeast showed difference in the growth activity of strains, mitochondrial function and the expression level of glycolytic genes.

Highlights

In both yeast and humans, the MTO1 gene encodes an evolutionarily conserved protein which works together with the proteins encoded by the MSS1 and MTO2 genes to catalyze the biosynthesis of 5-carboxymethylaminomethylation of the wobble uridine base in mttRNAGln, mt-tRNAGlu, and mt-tRNALys [1,2]
We found that the deletion of the MTO2 gene could significantly suppress the aminoglycoside-sensitivity of the mitochondrial 15S rRNA C1477G mutation in Saccharomyces cerevisiae through the up-regulation of the glycolytic pathway [8]
In the mto1(PR), the strain having both the mitochondrial 15S rRNA C1477G mutation and mto1 null mutation, glycolysis is up-regulated. This effect may be a compensation for weak mitochondrial function leading to the observation that this phenotype is less sensitive to neomycin

Summary

Introduction

In both yeast and humans, the MTO1 gene encodes an evolutionarily conserved protein which works together with the proteins encoded by the MSS1 and MTO2 genes to catalyze the biosynthesis of 5-carboxymethylaminomethylation (mnm5s2U34) of the wobble uridine base in mttRNAGln, mt-tRNAGlu, and mt-tRNALys [1,2] This modification is important to the accuracy and efficiency of mtDNA translation [2]. The mutation of nuclear modifier genes or the presence of Aminoglycoside antibiotics can work together with mtDNA mutation to affect the function of mitochondria. This has particular impact upon cells requiring lots of energy. The deletion of the nuclear gene MTO1 seemed to regulate neomycin sensitivity in yeast carrying the mitochondrial 15S rRNA C1477G mutation. The energy generated from glycolysis may compensate for the deficiencies in mitochondrial function and result in a phenotype less sensitive to neomycin

Materials and Methods

Results

Discussion