The effect of novobiocin on yeast topoisomerase type II.

Low concentrations of novobiocin are toxic to permeable yeast cells, but do not inhibit type II topoisomerase activity. Furthermore, the enzyme does not bind specifically to novobiocin-Sepharose. These observations are in agreement with genetical analyses. Mutations at a single locus that confer novobiocin resistance and temperature sensitivity exhibit a similar phenotype to cells treated with novobiocin, but are not topoisomerase II mutants.