Abstract
Aminoacylation of transfer RNAs (tRNAs) is essential for protein synthesis. A growing number of human diseases correlate with point mutations in tRNA genes within the mitochondrial genome. These tRNAs have unique sequences that suggest they have fragile structures. However, the structural significance of pathology-related tRNA mutations and their effects on molecular function have not been explored. Here, opthalmoplegia related mutants of a human mitochondrial tRNA have been investigated. Each mutation replaces either an A-U or G-C pair in the predicted secondary structure with an A-C pair. Aminoacylation of each mutant tRNA was severely attenuated. Moreover, each strongly inhibited aminoacylation of the wild type substrate, suggesting that the effects of these mutations might not be bypassed in the potentially heteroplasmic environment of mitochondria. The function of mutant tRNAs was rescued by single compensatory mutations that restored Watson-Crick base pairing and reintroduced stability into regions of predicted secondary structure, even though the pairs introduced were different from those found in the wild type tRNA. Thus, functional defects caused by a subset of pathogenic mutations may result from the inherent structural fragility of human mitochondrial tRNAs.
Original language | English (US) |
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Pages (from-to) | 862-865 |
Number of pages | 4 |
Journal | Nature Structural Biology |
Volume | 7 |
Issue number | 10 |
DOIs | |
State | Published - 2000 |
Externally published | Yes |
Funding
This work was supported by the National Institutes of Health and by a fellowship from the National Foundation for Cancer Research. S.O.K. was a NIH postdoctoral fellow. S.V.S. acknowledges an operating grant from Medical Research Council of Canada and a fellowship from le Fonds de la Recherche en Santé du Québec. We would like to acknowledge Cubist Pharmaceuticals and K. Shiba (Japanese Foundation for Cancer Research, Tokyo) for recombinant materials for the expression of human mitochondrial IleRS.
ASJC Scopus subject areas
- Genetics
- Structural Biology
- Biochemistry