Mitochondrial DNA topoisomerase I of Saccharomyces cerevisiae

摘要

A mitochondrial DNA topoisomerase (type I, ATP-independent) can be biochemically distinguished from the nuclear enzyme DNA topoisomerase I. This conclusion is based on the subcellular localization of the mitochondrial enzyme, its optimal reaction conditions and sensitivity to enzyme inhibitors. Unlike its nuclear counterpart, the mitochondrial DNA topoisomerase exhibits an absolute requirement for a divalent cation (Mg~2+ and Ca~2+ work equally well in vitro).