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Simultaneous Mapping and Quantitation of Ribonucleotides in Human Mitochondrial DNA
12:35

Simultaneous Mapping and Quantitation of Ribonucleotides in Human Mitochondrial DNA

Published on: November 14, 2017

tRNA punctuation model of RNA processing in human mitochondria

D Ojala, J Montoya, G Attardi

    Nature
    |April 9, 1981
    PubMed

    Insights

    Mitochondrial DNA (mtDNA) heavy strand RNA sequences for rRNA, poly(A)-containing RNA, and tRNA form a continuous transcript. This suggests transcription into a single polycistronic RNA molecule, processed into mature species.

    Area of Science:

    • Molecular Biology
    • Genetics
    • Biochemistry

    Background:

    • Mitochondrial DNA (mtDNA) encodes essential components for cellular respiration.
    • Understanding the transcription and processing of mtDNA is crucial for comprehending mitochondrial gene expression.

    Purpose of the Study:

    • To investigate the organization and processing of messenger RNA (mRNA) precursors on the heavy (H) strand of HeLa cell mtDNA.
    • To determine the relationship between coding sequences and tRNA genes at the 3'-end of H-strand mRNAs.

    Main Methods:

    • Partial sequencing of 3'-end proximal segments of putative mRNAs from HeLa cell mtDNA.
    • Alignment of sequenced mRNA segments with the corresponding DNA sequences.

    Main Results:

    • The 3'-end nucleotide of individual mRNA coding sequences was found to be immediately adjacent to a tRNA gene or another mRNA coding sequence.
    • These findings, combined with previous data, indicate a continuum of coding sequences for rRNA, poly(A)-containing RNA, and tRNA on the H-strand.

    Conclusions:

    • The heavy strand of mtDNA is likely transcribed as a single polycistronic RNA molecule.
    • This precursor RNA is subsequently processed into mature rRNA, poly(A)-containing RNA, and tRNA species through precise endonucleolytic cleavages, often associated with tRNA genes.

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