Mutation accumulation in transfer RNAs

Molecular evidence for Muller's ratchet in mitochondrial genomes

Research output: Contribution to journalArticle

155 Citations (Scopus)

Abstract

The accumulation of deleterious mutations is thought to be a major factor preventing the long-term persistence of obligately asexual lineages relative to their sexual ancestors. This phenomenon is also of potential relevance to sexual species that harbor asexually propagating organelle genomes. A comparative study of the transfer RNA genes in animal mitochondrial and nuclear genomes demonstrates that the former accumulate nucleotide substitutions much more rapidly than do the latter, and several lines of evidence are consistent with the idea that the excess substitutions are mildly deleterious. First, the average binding stability between complementary strands in the stems of mitochondrial tRNAs is less than half that in nuclear tRNAs. Second, most loop sizes in the mitochondrial tRNAs have experienced a net reduction in size over evolutionary time, and they are nearly 50 times more variable in the mitochondrial than in the nuclear genome. Third, although nearly 20% of the nucleotides in nuclear tRNA genes (particularly those involved in tertiary interactions) are invariant across all animal taxa and all tRNA species, there are no invariant sites in the mitochondrial tRNAs. These observations, as well as results from recent laboratory experiments, are consistent with the hypothesis that nonrecombining organelle genomes are subject to gradual loss of fitness due to the cumulative chance fixation of mildly deleterious mutations.

Original languageEnglish (US)
Pages (from-to)209-220
Number of pages12
JournalMolecular Biology and Evolution
Volume13
Issue number1
DOIs
StatePublished - Jan 1 1996
Externally publishedYes

Fingerprint

organelle genome
transfer RNA
Mitochondrial Genome
Transfer RNA
nuclear genome
RNA
mutation
genome
nucleotides
animals
ancestry
substitution
genes
Genome
stems
gene
animal
Organelles
fixation
Nucleotides

Keywords

  • deleterious mutation
  • insertion/deletion rate
  • mitochondrial genome
  • Muller's ratchet
  • substitution rate
  • transfer RNA

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Molecular Biology
  • Genetics

Cite this

Mutation accumulation in transfer RNAs : Molecular evidence for Muller's ratchet in mitochondrial genomes. / Lynch, Michael.

In: Molecular Biology and Evolution, Vol. 13, No. 1, 01.01.1996, p. 209-220.

Research output: Contribution to journalArticle

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