TABLE 2.

Summary of known regulation for the main topoisomerases in bacteria and eukaryotes

	Name	Gene expression	Transcript	Enzyme
	DNA relaxation
Bacteria	Topo I	Induced by supercoiled DNA	N/D	Constitutive, possibly inhibited by anaerobiosis
Eukaryote	Topo I	Constitutive	N/D	Activated by polyamines
	DNA compaction
Bacteria	DNA gyrase	Induced by relaxed DNA	N/D	Activity correlates with [ATP]/[ADP] ratio, activated by polyamines. Putative chaperone
	Decatenases
Bacteria	Topo IV	Cell cycle‐regulated in Caulobacter	N/D	N/D
Eukaryote	TOP2A	Peaks in G2/M phase, regulated by many cell cycle‐ and tissue‐dependent transcription factors	Stabilized in G2/M phases	Activity and stability regulated by ubiquitinylation, SUMOylation, and phosphorylation
	TOP2B	Mostly constitutive, some tissue dependence	N/D	Activity regulated by SUMOylation and phosphorylation

Abbreviation: N/D, no data available.