Structural probing of a pathogenic tRNA dimer.

The A3243G mutation within the human mitochondrial (hs mt) tRNALeuUUR gene is associated with maternally inherited deafness and diabetes (MIDD) and other mitochondrial encephalopathies. One of the most pronounced structural effects of this mutation is the disruption of the native structure through stabilization of a high-affinity dimeric complex. We conducted a series of studies that address the structural properties of this tRNA dimer, and we assessed its formation under physiological conditions.

Synthesis, characterization, and cellular uptake of DNA-binding rose bengal peptidoconjugates.

Peptide conjugates of the xanthene dye rose bengal (RB) are described featuring sequences that promote DNA binding. The complexation of these conjugates with DNA causes efficient quenching of the fluorophore singlet state and suppresses singlet oxygen production. When incubated with human cells, the RB conjugates pass through the cell membrane but are not visualized in the nucleus.

Interdomain communication between weak structural elements within a disease-related human tRNA.

The structure of the human mitochondrial (hs mt) tRNALeu(UUR) features several domains that are predicted to exhibit limited thermodynamic stability. An elevated frequency of disease-related mutations within these domains suggests a link between structural instability and the functional effects of pathogenic mutations. A series of tRNAs featuring mutations within the D and anticodon stems were prepared and investigated using nuclease probing.

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.

The pathogenic U3271C human mitochondrial tRNA(Leu(UUR)) mutation disrupts a fragile anticodon stem.

The U3271C mutation affecting the human mitochondrial transfer RNA(Leu(UUR)) (hs mt tRNA) is correlated with diabetes and mitochondrial encephalopathies. We have explored the relationship between the structural effects of this mutation and its impact on function using chemical probing experiments and in vitro aminoacylation assays to investigate a series of tRNA constructs. Chemical probing experiments indicate that the U3271C substitution, which replaces an AU pair with a CA mispair, significantly destabilizes the anticodon stem.

Dimerization of a pathogenic human mitochondrial tRNA.

Mutations of human mitochondrial transfer RNA (tRNA) are implicated in a variety of multisystemic diseases. The most prevalent pathogenic mitochondrial mutation is the A3243G substitution within the gene for tRNA(Leu(UUR)). Here we describe the pronounced structural change promoted by this mutation.