Acquisition of the wobble modification in mitochondrial tRNALeu(CUN) bearing the G12300A mutation suppresses the MELAS molecular defect.

TitleAcquisition of the wobble modification in mitochondrial tRNALeu(CUN) bearing the G12300A mutation suppresses the MELAS molecular defect.
Publication TypeJournal Article
Year of Publication2006
AuthorsKirino, Y, Yasukawa, T, Marjavaara, SK, Jacobs, HT, Holt, IJ, Watanabe, K, Suzuki, T
JournalHum Mol Genet
Volume15
Issue6
Pagination897-904
Date Published2006 Mar 15
ISSN0964-6906
KeywordsAdenosine, Anticodon, Base Sequence, Cell Line, Tumor, Guanosine, Humans, MELAS Syndrome, Molecular Sequence Data, Nucleic Acid Conformation, Point Mutation, RNA, RNA, Mitochondrial, RNA, Transfer, Leu, Suppression, Genetic, Uridine
Abstract

The A3243G mutation in the mitochondrial gene for human mitochondrial (mt) tRNA(Leu(UUR)), responsible for decoding of UUR codons, is associated with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS). We previously demonstrated that this mutation causes defects in 5-taurinomethyluridine (taum(5)U) modification at the anticodon first (wobble) position of the mutant mt tRNA(Leu(UUR)), leading to a UUG decoding deficiency and entraining severe respiratory defects. In addition, we previously identified a heteroplasmic mutation, G12300A, in the other mt leucine tRNA gene, mt tRNA(Leu(CUN)), which functions as a suppressor of the A3243G respiratory defect in cybrid cells containing A3243G mutant mtDNA. Although the G12300A mutation converts the anticodon sequence of mt tRNA(Leu(CUN)) from UAG to UAA, this tRNA carrying an unmodified wobble uridine still cannot decode the UUG codon. Mass spectrometric analysis of the suppressor mt tRNA(Leu(CUN)) carrying the G12300A mutation from the phenotypically revertant cells revealed that the wobble uridine acquires de novo taum(5)U modification. In vitro translation confirmed the functionality of the suppressor tRNA for decoding UUG codons. These results demonstrate that the acquisition of the wobble modification in another isoacceptor tRNA is critical for suppressing the MELAS mutation, and they highlight the primary role of the UUG decoding deficiency in the molecular pathogenesis of MELAS syndrome.

DOI10.1093/hmg/ddl007
Alternate JournalHum. Mol. Genet.
Citation Key10.1093/hmg/ddl007
PubMed ID16446307
Grant ListMC_U105663140 / / Medical Research Council / United Kingdom