A human mitochondrial GTP binding protein related to tRNA modification may modulate phenotypic expression of the deafness-associated mitochondrial 12S rRNA mutation.
Human mitochondrial 12S rRNA A1555G mutation has been found to be associated with deafness. However, putative nuclear modifier gene(s) has been proposed to regulate the phenotypic expression of this mutation. In yeast cells, mutant alleles of MSS1, encoding a mitochondrial GTP-binding protein, manifest a respiratory-deficient phenotype only when coupled with mitochondrial 15S rRNA P(R)(454) mutation corresponding to human A1555G mutation. This suggests that an MSS1-like modifier gene may influence the phenotypic expression of the A1555G mutation. We report here the identification and characterization of human MSS1 homolog, GTPBP3, the first identified vertebrate gene related to mitochondrial tRNA modification. The Gtpbp3 is the mitochondrial GTPase evolutionarily conserved from bacteria to mammals. Functional conservation of this protein is supported by the observation that isolated human GTPBP3 cDNA can complement the respiratory-deficient phenotype of yeast mss1 cells carrying P(R)(454) mutation. GTPBP3 is ubiquitously expressed in various tissues as multiple transcripts, but with a markedly elevated expression in tissues of high metabolic rates. We showed that Gtpbp3 localizes in mitochondrion. These observations suggest that the human GTPBP3 is a structural and functional homolog of yeast MSS1. Thus, allelic variants in GTPBP3 could, if they exist, modulate the phenotypic manifestation of human mitochondrial A1555G mutation.
Li
Xiaoming
X
Division and Program in Human Genetics and Center for Hearing and Deafness Research, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039, USA.
Guan
Min-Xin
MX
D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D003638:Deafness / Q000235:genetics*; D004926:Escherichia coli / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000235:genetics; D019204:GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology; D005816:Genetic Complementation Test; D005947:Glucose / Q000494:pharmacology; D005990:Glycerol / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics* / Q000502:physiology; D009690:Nucleic Acid Conformation; D010641:Phenotype; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D012335:RNA, Ribosomal / Q000235:genetics*; D012343:RNA, Transfer / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
D018076:DNA, Complementary; D009687:Nuclear Proteins; D012333:RNA, Messenger; D012335:RNA, Ribosomal; C075526:RNA, ribosomal, 12S; D029701:Saccharomyces cerevisiae Proteins; D012343:RNA, Transfer; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; C498989:GTPBP3 protein, human; C082241:MSS1 protein, S cerevisiae; D005947:Glucose; D005990:Glycerol