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- **********************************
- * DNA topoisomerase II signature *
- **********************************
-
- DNA topoisomerase II (EC 5.99.1.3) [1,2,3] is one of the two types of enzymes
- that catalyze the interconversion of topological isomers of DNA. Type II
- topoisomerases 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). In 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 Escherichia coli, 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 relation between the different subunits is shown in the
- following representation:
-
- <----------------About-1400-residues----------------------->
-
- [----------Protein 39-*-----][----Protein 52----] Phage T4
- [----------gyrB-------*-----][--------gyrA-----------------] Prokaryote II
- Archaebacteria
- [----------parE-------*-----][--------parD-----------------] Prokaryote IV
- [---------------------*------------------------------------] Eukaryote and
- ASF
- '*': Position of the pattern.
-
- As a signature pattern for this family of proteins, we have selected a region
- that contains a highly conserved pentapeptide. The pattern is located in gyrB,
- in parE, and in protein 39 of phage T4 topoisomerase.
-
- -Consensus pattern: [LIVMA]-x-E-G-[DN]-S-A-x-[STAG]
- -Sequences known to belong to this class detected by the pattern: ALL.
- -Other sequence(s) detected in SWISS-PROT: NONE.
- -Last update: October 1993 / Pattern and text revised.
-
- [ 1] Sternglanz R.
- Curr. Opin. Cell Biol. 1:533-535(1990).
- [ 2] Bjornsti M.-A.
- Curr. Opin. Struct. Biol. 1:99-103(1991).
- [ 3] Wyckoff E., Natalie D., Nolan J.M., Lee M., Hsieh T.-S.
- J. Mol. Biol. 205:1-13(1989).
-