Analyzing Distribution on Yeast Chromosomes

In vertebrate cells, DNA topoisomerase II (Topo II), named Top2 in yeast, localizes along chromosome axes early in mitosis and concentrates within centromeric chromatin during metaphase. The factors controlling these changes in enzyme distribution are largely unknown. Insight into Topo II dynamics could potentially be derived through genetic approaches in yeast. In practice, however, the small size and limited compaction of yeast chromosomes has precluded a detailed analysis of Top2 localization along mitotic chromosomes. As an alternative approach, we describe a method for examining Top2 distribution using chromatin immunoprecipitation (ChIP). By adding a detergent solubilization step, this method allows efficient recovery of DNA sequences associated with Top2 in the insoluble chromosome scaffold fraction.