Transposon Tn5 target specificity: preference for insertion at G/C pairs
Lodge, J.K.; Weston-Hafer, K.; Berg, D.E.
Genetics 120(3): 645-650
1988
ISSN/ISBN: 0016-6731 PMID: 2852135 Document Number: 310047
The procaryotic transposon Tn5 inserts into many different sites within a single gene, but some sites (hotspots) are targeted repeatedly. Hotspots are not closely related in sequence, but most have G/C pairs at the ends of the nine base pairs duplicated by Tn5 insertion. In pBR322, the major hotspot coincides with the "-10 region" of the tet promoter. We mutated the G/C pairs at this hotspot and assayed for insertion into hotspot I, resistance to tetracycline, and plasmid supercoiling. We found that changing the G/C pairs to A/T pairs reduced the frequency of insertion into the hotspot by at least fivefold. The reduction in hotspot use caused by these G/C to A/T changes was not attributable to changes in plasmid supercoiling or tet promoter strength.