Conserved Site

DNA topoisomerase, type IIA, conserved site (IPR018522)

Short name: TopoIIA_CS


DNA topoisomerases regulate the number of topological links between two DNA strands (i.e. change the number of superhelical turns) by catalysing transient single- or double-strand breaks, crossing the strands through one another, then resealing the breaks [PMID: 7770916]. These enzymes have several functions: to remove DNA supercoils during transcription and DNA replication; for strand breakage during recombination; for chromosome condensation; and to disentangle intertwined DNA during mitosis [PMID: 12042765, PMID: 11395412]. DNA topoisomerases are divided into two classes: type I enzymes (EC:; topoisomerases I, III and V) break single-strand DNA, and type II enzymes (EC:; topoisomerases II, IV and VI) break double-strand DNA [PMID: 12596227].

Type II topoisomerases are ATP-dependent enzymes, and can be subdivided according to their structure and reaction mechanisms: type IIA (topoisomerase II or gyrase, and topoisomerase IV) and type IIB (topoisomerase VI). These enzymes are responsible for relaxing supercoiled DNA as well as for introducing both negative and positive supercoils [PMID: 7980433].

DNA topoisomerase II (EC: [PMID: 2560656, PMID: 7773745, PMID: 7770916] is one of the two types of enzyme that catalyze the interconversion of topological DNA isomers. Type II topoisomerases are ATP-dependent and act by passing a DNA segment through a transient double-strand break. Topoisomerase II is found in phages, archaebacteria, prokaryotes, eukaryotes, and in African Swine Fever virus (ASF). Bacteriophage T4 topoisomerase II consists of three subunits (the product of genes 39, 52 and 60). In prokaryotes and in archaebacteria the enzyme, known as DNA gyrase, consists of two subunits (genes GyrA and GyrB). In some bacteria, a second type II topoisomerase has been identified; it is known as topoisomerase IV and is required for chromosome segregation, it also consists of two subunits (genes parC and parE). In eukaryotes, type II topoisomerase is a homodimer.

There are many regions of sequence homology between the different subtypes of topoisomerase II. The signature pattern used in this entry is a highly conserved pentapeptide, which is located in GyrB, in ParE, and in protein 39 of phage T4 topoisomerase.

GO terms

Biological Process

GO:0006265 DNA topological change

Molecular Function

GO:0005524 ATP binding
GO:0003677 DNA binding
GO:0003918 DNA topoisomerase type II (ATP-hydrolyzing) activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns