• DOI:10.1038/357173A0
• Corpus ID: 4370160

Self-splicing introns in tRNA genes of widely divergent bacteria

@article{ReinholdHurek1992SelfsplicingII,
  title={Self-splicing introns in tRNA genes of widely divergent bacteria},
  author={Barbara Reinhold-Hurek and David. A. Shub},
  journal={Nature},
  year={1992},
  volume={357},
  pages={173-176}
}

• B. Reinhold-Hurek, D. Shub
• Published 14 May 1992
• Biology
• Nature

THE organization of eukaryotic genes into exons separated by introns has been considered as a primordial arrangement1,2 but because it does not exist in eubacterial genomes it may be that introns are relatively recent acquisitions3. A self-splicing group I intron has been found in cyanobacteria at the same position of the same gene (that encoding leucyl transfer RNA, UAA anticodon) as a similar group I intron of chloroplasts4,5, which indicates that this intron predates the invasion of eukaryotic cells by cyanobac-terial endosymbionts. But it is not clear from this isolated example whether introns are more generally present in different genes or in more diverse branches of the eubacteria. Many mitochondria have intron-rich genomes and were probably derived from the alpha subgroup of the purple bacteria6 (or Proteobacteria7), so ancient introns might also have been retained in these bacteria. We describe here the discovery of two small (237 and 205 nucleotides) self- splicing group I introns in members of two proteobacterial subgroups, Agrobacterium tumefaciens (α) and Azoarcus sp. (β). The introns are inserted in genes for tRNAArg and tRNAIle respectively, after the third anticodon nucleotide. Their occurrence in different genes of phyogenetically diverse bacteria indicates that group I introns have a widespread distribution among eubacteria.