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Reduction of mitochondrial tRNALeu(UUR) aminoacylation by some MELAS-associated mutations

Rui Hao1, Yong-Neng Yao, Yong-Gang Zheng

  • 1State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, The Chinese Academy of Sciences, PR China.

FEBS Letters
|December 8, 2004
PubMed

Insights

Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) is linked to mutations in the mitochondrial tRNALeu(UUR) gene. These mutations reduce the gene

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) is a rare mitochondrial DNA disorder.
  • Five single nucleotide substitutions in the human mitochondrial tRNALeu(UUR) gene are associated with MELAS.

Purpose of the Study:

  • To investigate the functional impact of five MELAS-associated mutations on the human mitochondrial tRNALeu(UUR) transcript.
  • To assess the aminoacylation capacity and structural integrity of mutant tRNALeu(UUR) transcripts.

Main Methods:

  • In vitro transcription of wild-type and mutant hmtRNALeu(UUR) transcripts.
  • Aminoacylation assays using Leucyl-tRNA synthetase (LeuRS).
  • Thermal denaturation experiments to assess RNA structural stability.

Main Results:

  • All five MELAS-associated mutations reduced the aminoacylation capacity of hmtRNALeu(UUR) transcripts to varying degrees.
  • The A3243G and T3291C mutants exhibited reduced aminoacylation and displayed fragile structures.
  • The T3291C mutant demonstrated inhibitory effects on wild-type hmtRNALeu(UUR) aminoacylation.

Conclusions:

  • The studied mutations impair tRNALeu(UUR) function, contributing to MELAS pathogenesis.
  • Structural instability and potential inhibitory activity of mutants like T3291C may disrupt mitochondrial protein synthesis in heteroplasmic environments.

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