Housekeeping recA gene interrupted by group II intron in the thermophilic Geobacillus kaustophilus.

Most of group II introns are found in intergenes and CDSs with unknown functions, but not in housekeeping genes. In particular, no group II intron within the housekeeping recA gene has been reported either in eukaryotic genomes or in prokaryotic genomes. In this study, we found that the recA gene of the thermophilic Geobacillus kaustophilus genome is interrupted by a group II intron (Gk. Int1), and that Gk.Int1 can splice in temperatures above 70 degrees C in vivo. Here, we report the first prokaryotic group II intron to be found in a housekeeping gene, the characteristics of its self-splicing in vivo and in vitro, and our conclusion that the recA gene functions through the self-splicing of Gk.Int1. It is suggested that the amelioration of Gk.Int1 intron has occurred recently, and that it is still in the process of evolution to the recipient genome.