Decreased aminoacylation of mutant tRNAs in MELAS but not in MERRF patients
Open Access
- 1 March 2000
- journal article
- case report
- Published by Oxford University Press (OUP) in Human Molecular Genetics
- Vol. 9 (4) , 467-475
- https://doi.org/10.1093/hmg/9.4.467
Abstract
Mutations in human mitochondrial tRNA genes are associated with a number of multisystemic disorders. Using an assay that combines tRNA oxidation and circularization we have determined the relative amounts and states of aminoacylation of mutant and wild-type tRNAs in tissue samples from patients with MELAS syndrome (mito‐ chondrial myopathy, encephalopathy, lactic acidosis, stroke-like episodes) and MERRF syndrome (myoclonus epilepsy with ragged red fibers), respectively. In most, but not all, biopsies from MELAS patients carrying the A3243G substitution in the mitochondrial tRNALeu(UUR) gene, the mutant tRNA is under-represented among processed and/or aminoacylated tRNAs. In contrast, in biopsies from MERRF patients harboring the A8344G substitution in the tRNALys gene neither the relative abundance nor the aminoacylation of the mutated tRNA is affected. Thus, whereas the A3243G mutation may contribute to the pathogenesis of MELAS by reducing the amount of aminoacylated tRNALeu, the A8344G mutation does not affect tRNALys function in the same way.Keywords
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