Topoisomerase type II (Topo II)

Topoisomerase type II is an enzyme that cuts both strands of the DNA double helix to manage supercoils, tangles, and knots, passing one DNA duplex (T-segment) through a transient break in another (G-segment) in an ATP-dependent manner. It consists of ATPase, Toprim, DNA-binding, and variable C-terminal domains; eukaryotic forms are homodimers (A2), prokaryotic are heterotetramers (A2B2). The mechanism involves N-gate, DNA-gate, and C-gate for strand passage, forming phosphotyrosine linkages, with religation after passage; it changes DNA linking number by 2 units and is essential for disentangling chromosomes without supercoiling DNA.

Other names

Type II topoisomeraseType IIA topoisomeraseType IIB topoisomerase