DNA Gyrase is:

Topoisomerases Relieves supercoils. Cut and reseal DNA and relieve positive supercoils. Don't use ATP. Gain energy from the cleavage of the phosphodiester bond. DNA Gyrase: Counterpa of Topoisomerase II in prokaryotes. Introduces negative supercoils (underwinding is known as negative supercoiling) and Uses ATP Topoisomerase I Topoisomerase II Makes cut on single strand Makes cut on both strands Formation of a covalent DNA-enzyme complex preserves the free energy. ATP is not needed. ATP is needed. Relaxes negative supercoils in E. coli; Both negative and positive in Eukaryotes. Relaxes both negative & positive supercoils. +ve supercoil is relieved by introducing -ve supercoils.