Summary: DNA topoisomerase
DNA topoisomerase Provide feedback
This subfamily of topoisomerase is divided on the basis that these enzymes preferentially relax negatively supercoiled DNA, from a 5' phospho- tyrosine linkage in the enzyme-DNA covalent intermediate and has high affinity for single stranded DNA.
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This tab holds annotation information from the InterPro database.
InterPro entry IPR013497
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 [PUBMED: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 [PUBMED:12042765, PUBMED: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 [PUBMED:12596227].
Type I topoisomerases are ATP-independent enzymes (except for reverse gyrase), and can be subdivided according to their structure and reaction mechanisms: type IA (bacterial and archaeal topoisomerase I, topoisomerase III and reverse gyrase) and type IB (eukaryotic topoisomerase I and topoisomerase V). These enzymes are primarily responsible for relaxing positively and/or negatively supercoiled DNA, except for reverse gyrase, which can introduce positive supercoils into DNA.
Type IA topoisomerases are comprised of four domains that together form a toroidal structure with a central hole large enough to accommodate single- and double-stranded DNA: an N-terminal alpha/beta Toprim domain, domain 2 and the C-terminal domain 4 are winged-helix domains, and domain 3 is a beta-barrel. Domains 1 (Toprim) and 3 form the active site of the enzyme, while the winged helix domains 2 and 4 form a single-strand DNA-binding groove [PUBMED:14604525, PUBMED:10574789]. This entry represents the central portion of the enzyme, which covers domains 2 and 3 in topoisomerase type IA enzymes.
More information about this protein can be found at Protein of the Month: DNA Topoisomerase [PUBMED:].
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Cellular component||chromosome (GO:0005694)|
|Molecular function||DNA binding (GO:0003677)|
|DNA topoisomerase activity (GO:0003916)|
|Biological process||DNA topological change (GO:0006265)|
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Curation and family details
|Seed source:||Pfam-B_505 (release 3.0)|
|Author:||Finn RD, Bateman A|
|Number in seed:||126|
|Number in full:||9972|
|Average length of the domain:||388.60 aa|
|Average identity of full alignment:||29 %|
|Average coverage of the sequence by the domain:||56.06 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||15|
|Download:||download the raw HMM for this family|
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Topoisom_bac domain has been found. There are 35 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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