Demonstration that the group II intron from the clostridial conjugative transposon Tn5397 undergoes splicing in vivo

Previous work has identified the conjugative transposon Tn5397 from Clostri dium difficile. This element was shown to contain a group II intron. Tn5397 can be conjugatively transferred from C. difficile to Bacillus subtilis. I n this work we show that the intron is spliced in both these hosts and that nonspliced RNA is also present. We constructed a mutation in the open read ing frame within the intron, and this prevented splicing but did not preven t the formation of the circular form of the conjugative transposon (the lik ely transposition intermediate) or decrease the frequency of intergeneric t ransfer of Tn5397. Therefore, the intron is spliced, but splicing is not re quired for conjugation of Tn5397.