Topoisomerase IV is essential for chromosome segregation; it is the principal protein responsible for decatenating newly replicated chromosomes (PubMed:9334322). It relaxes supercoiled DNA (PubMed:12269820, PuMed:16023670, PubMed:21300644). MukB stimulates the relaxation activity of topoisomerase IV and also has a modest effect on decatenation (PubMed:20921377). ATP-dependent breakage, passage and rejoining of double-stranded DNA. Inhibited by quinolones. Heterotetramer composed of ParC and ParE. Interacts with MukB. Belongs to the type II topoisomerase GyrA/ParC subunit family. ParC type 1 subfamily.