Evidence of the presence of tRNAfMet group I intron in the marine cyanobacterium Synechococcus elongatus

Self-splicing group I introns in tRNA anticodon loops have been found in diverse groups of bacteria. In this work, we identified tRNAfMet group I introns in six strains of marine Synechococcus elongatus. Introns with sizes around 280 bp were consistently obtained in all the strains tested. In a phylogenetic analysis using the nucleotide sequence determined in this study with other cyanobacterial tRNAfMet and tRNALeu intron sequences, the Synechococcus sequence was grouped together with the sequences from other unicellular cyanobacterial strains. Interestingly, the phylogenetic tree inferred from the intronic sequences clearly separates the different tRNA introns, suggesting that each family has its own evolutionary history.