A pathogenesis-associated mutation in human mitochondrial tRNALeu(UUR) leads to reduced 3'-end processing and CCA addition

J Mol Biol. 2004 Mar 26;337(3):535-44. doi: 10.1016/j.jmb.2004.02.008.


Point mutations in mitochondrial tRNAs can cause severe multisystemic disorders such as mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) and myoclonus epilepsy with ragged-red fibers (MERRF). Some of these mutations impair one or more steps of tRNA maturation and protein biosynthesis including 5'-end-processing, post-transcriptional base modification, structural stability, aminoacylation, and formation of tRNA-ribosomal complexes. tRNALeu(UUR), an etiologic hot spot for such diseases, harbors 20 of more than 90 disease-associated mutations described to date. Here, the pathogenesis-associated base substitutions A3243G, T3250C, T3271C, A3302G and C3303T within this tRNA were tested for their effects on endonucleolytic 3'-end processing and CCA addition at the tRNA 3'-terminus. Whereas mutations A3243G, A3302G and C3303T reduced the efficiency of 3'-end cleavage, only the C3303T substitution was a less efficient substrate for CCA addition. These results support the view that pathogenesis may be elicited through cumulative effects of tRNA mutations: a mutation can impede several pre-tRNA processing steps, with each such reduction contributing to the overall impairment of tRNA function.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Humans
  • Kinetics
  • Mitochondrial Diseases / genetics*
  • Nucleic Acid Conformation
  • Point Mutation*
  • RNA / genetics*
  • RNA / physiology
  • RNA 3' End Processing*
  • RNA Nucleotidyltransferases / metabolism
  • RNA, Mitochondrial
  • RNA, Transfer, Leu / genetics*
  • RNA, Transfer, Leu / physiology


  • RNA, Mitochondrial
  • RNA, Transfer, Leu
  • RNA
  • RNA Nucleotidyltransferases
  • tRNA nucleotidyltransferase