Group II intron and repeat-rich red algal mitochondrial genomes demonstrate the dynamic recent history of autocatalytic RNAs

Dongseok Kim, Jun Mo Lee, Chung Hyun Cho, Eun Jeung Kim, Debashish Bhattacharya, Hwan Su Yoon

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Background: Group II introns are mobile genetic elements that can insert at specific target sequences, however, their origins are often challenging to reconstruct because of rapid sequence decay following invasion and spread into different sites. To advance understanding of group II intron spread, we studied the intron-rich mitochondrial genome (mitogenome) in the unicellular red alga, Porphyridium. Results: Analysis of mitogenomes in three closely related species in this genus revealed they were 3–6-fold larger in size (56–132 kbp) than in other red algae, that have genomes of size 21–43 kbp. This discrepancy is explained by two factors, group II intron invasion and expansion of repeated sequences in large intergenic regions. Phylogenetic analysis demonstrates that many mitogenome group II intron families are specific to Porphyridium, whereas others are closely related to sequences in fungi and in the red alga-derived plastids of stramenopiles. Network analysis of intron-encoded proteins (IEPs) shows a clear link between plastid and mitochondrial IEPs in distantly related species, with both groups associated with prokaryotic sequences. Conclusion: Our analysis of group II introns in Porphyridium mitogenomes demonstrates the dynamic nature of group II intron evolution, strongly supports the lateral movement of group II introns among diverse eukaryotes, and reveals their ability to proliferate, once integrated in mitochondrial DNA.

Original languageEnglish (US)
Article number2
JournalBMC Biology
Issue number1
StatePublished - Dec 2022

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Structural Biology
  • Ecology, Evolution, Behavior and Systematics
  • Physiology
  • General Biochemistry, Genetics and Molecular Biology
  • General Agricultural and Biological Sciences
  • Plant Science
  • Developmental Biology
  • Cell Biology


  • Genome expansion
  • Group II introns
  • Horizontal gene transfer
  • Red algae
  • Repeated sequences


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