a. Nucleotide sequence of the mutated rolA intron and schematic drawing of the DefH9-RI-iaaM chimeric gene, derived from the DefH9-iaaM gene. The mutated splicing sites (GT and GA changed to GA and AA, respectively) are indicated in bold. In vitro transcription (left panel) and in vitro translation analysis (right panel) of the DNA fragments corresponding to the transcribed regions of DefH9-RI-iaaM (lanes 1 and 4) and DefH9-iaaM (lanes 2 and 5) genes, subcloned in bluescript vector. Lanes 3 and 6: the in vitro translation analysis was performed either without any added DNA or with the vector alone, respectively. The predicted molecular mass of iaaM is 61.8 kDa.