Excision of transposon Tn917 in Bacillus subtilis.

Excision of Tn917 from chromosomal sites in B. subtilis is characterized by reversion studies. We propose different modes of excision depending on the site of transposon insertion. Excision takes place as precise excision in one step which results in reversion of the mutant phenotype, or by a two-step process where nearly precise excision of the transposon moiety is followed by precise excision of the nearly precise excision remnants. For this type of transposons a minor pathway or nonreplicative transposition is proposed to be connected with precise excision.