Relaxes both positive and negative supercoils and exhibits a strong decatenase and unknotting activity; it cannot introduce DNA supercoils (PubMed:7961685). ATP is absolutely required for DNA cleavage; the nonhydrolyzable analog AMP-PNP generates nicked or linear products from a supercoiled dsDNA substrate. Generates staggered two-nucleotide long 5' overhangs. The enzyme is covalently attached transiently to the 5'-ends of the cleaved strands (PubMed:11485995). ATP-dependent breakage, passage and rejoining of double-stranded DNA. Not inhibited by the DNA gyrase inhibitor novobiocin, instead inhibited by eukaryotic topoisomerase inhibitors such as m- and o-amsacrine, ellipticine, and the quinolone CP-115,953 (PubMed:7961685). Optimum temperature is 70-80 degrees Celsius. Homodimer. Heterotetramer of two Top6A and two Top6B chains. Belongs to the TOP6A family.