Dictyostelium discoideum plasmid containing an AP-endonuclease upstream sequence: bleomycin induction of a luciferase reporter.

A sequence of 1624 bp 5' to the apurinic/apyrimidinic (AP) endonuclease structural gene of Dictyostelium discoideum (APEA) has been inserted upstream of the luciferase reporter gene in pVTL2, an autonomously replicating nuclear plasmid in this organism. Cells transformed with this plasmid, designated pVTL-AL, displayed strong luciferase induction during treatment with the DNA-damaging agent bleomycin. For example, a luciferase activity of 45-fold above the constitutive level was observed for 20 hours of growth in axenic medium with 0.002 U/mL of bleomycin. The response was bleomycin concentration-dependent. Cell survival was greater than 90% for all treatments. The level of luciferase expression was highly dependent on the cell growth conditions, with the greatest induction observed for stationary phase axenically-grown cells. This effect may be related to a variation of plasmid copy number with growth conditions. Copyright 2001 Wiley-Liss, Inc.