Impact of disease-related mitochondrial mutations on tRNA structure and function.

Over 150 mutations with documented pathogenicity have been identified within the human mitochondrial genome. More than half of the disease-related mutations are located within tRNA genes, a remarkable trend, given that these sequences comprise only 10% of the genome. The discovery of diseases correlated with mitochondrial tRNA mutations provides the first example of a class of pathologies related to RNA function, and the study of these tRNAs provides an interesting opportunity to explore the relationship between physiology and tRNA function. Investigations of both cellular and molecular effects have provided important insights into the structural and functional defects caused by the mutations. The picture that emerges from varied studies is that the effects of tRNA mutations are probably multifaceted and complex, but can be traced to the destabilization of structural features that destroy the native tRNA fold required for all aspects of function.