ONE-ENDED INSERTION OF IS911

An apparently nonreplicative integration reaction mediated by the inse rtion sequence IS911 has been analyzed. It is shown to involve the rig ht-end inverted repeat (IRR) of the element and sequences in the flank ing vector DNA. The flanking sequences appear to behave as a surrogate IS911 end, since integration is greatly reduced when limited similari ties with IRR are eliminated by site-directed mutagenesis. Data are pr esented which suggest that the activity of the IRR junction results fr om the proximity of the transposase gene and may therefore reflect pre ferential transposase recognition of IRR in cis.