Pathogenesis-related mutations in the T-loops of human mitochondrial tRNAs affect 3' end processing and tRNA structure.

ABSTRACT: Numerous mutations in the mitochondrial genome are associated with maternally transmitted diseases and syndromes that affect muscle and other high energy-demand tissues. The mitochondrial genome encodes 13 polypeptides, 2 rRNAs and 22 interspersed tRNAs via long bidirectional polycistronic primary transcripts, requiring precise excision of the tRNAs. Despite making up only ~10% of the mitochondrial genome, tRNA genes harbor most of the pathogenesis-related mutations. tRNase Z endonucleolytically removes the pre-tRNA 3' trailer. The flexible arm of tRNase Z recognizes and binds the elbow (including the T-loop) of pre-tRNA. Pathogenesis-related T-loop mutations in mitochondrial tRNAs could thus affect tRNA structure, reduce tRNase Z binding and 3' processing, and consequently slow mitochondrial protein synthesis. Here we inspect the effects of pathogenesis-related mutations in the T-loops of mitochondrial tRNAs on pre-tRNA structure and tRNase Z processing. Increases in K(M) arising from 59A > G substitutions in mitochondrial tRNA(Gly) and tRNA(Ile) accompany changes in T-loop structure, suggesting impaired substrate binding to enzyme.

SUBMITTER: Levinger L 

PROVIDER: S-EPMC3384583 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature