Group II introns as controllable gene targeting vectors for genetic manipulation of bacteria

Mobile group II introns can be retargeted to insert into virtually any desi red DNA target. Here we show that retargeted group II introns can be used f or highly specific chromosomal gene disruption in Escherichia coli and othe r bacteria at frequencies of 0.1-22%. Furthermore, the introns can be used to introduce targeted chromosomal breaks, which can be repaired by transfor mation with a homologous DNA fragment, enabling the introduction of point m utations. Because of their wide host range, mobile group II introns should be useful for genetic engineering and functional genomics in a wide variety of bacteria.