Transposon Tn5 target specificity: preference for insertion at G/C pairs.
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.
Lodge
J K
JK
Department of Microbiology and Immunology, Washington University Medical School, St. Louis, Missouri 63110.
Weston-Hafer
K
K
Berg
D E
DE
D001482:Base Composition; D003596:Cytosine / Q000502:physiology; D004251:DNA Transposable Elements; D004278:DNA, Superhelical / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D006147:Guanine / Q000502:physiology; D009154:Mutation; D010957:Plasmids; D013753:Tetracycline Resistance / Q000235:genetics
D004251:DNA Transposable Elements; D004278:DNA, Superhelical; D006147:Guanine; D003596:Cytosine