Novobiocin inhibits the SV40 enhancer activity

Using a transient expression assay, we have analysed the effect of novobiocin, DNA topoisomerase II inhibitor, on simian virus 40(SV40) enhancer activities. We used the recombinant clones containing type I or II collagen promoters placed upstream of the bacterial chloramphenicol acetyltransferase (CAT) gene with or without SV40 enhancer. We observed the expected increase in CAT activities due to the presence of the SV40 enhancer. Interestingly, CAT gene expression of the enhancer-containing constructs were inhibited more sensitively by novobiocin than that of the enhancer-less construct. This findings lead us propose that DNA superhelicity mediated by topoisomeraseII is one of the important factor for the manifestation of SV40 enhancer activity.