Summary: DNA gyrase B subunit, carboxyl terminus
DNA gyrase B subunit, carboxyl terminus Provide feedback
The amino terminus of eukaryotic and prokaryotic DNA topoisomerase II are similar, but they have a different carboxyl terminus. The amino-terminal portion of the DNA gyrase B protein is thought to catalyse the ATP-dependent super-coiling of DNA. See PF00204. The carboxyl-terminal end supports the complexation with the DNA gyrase A protein and the ATP-independent relaxation. This family also contains Topoisomerase IV. This is a bacterial enzyme that is closely related to DNA gyrase, .
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This tab holds annotation information from the InterPro database.
InterPro entry IPR002288
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 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 [PUBMED:7980433].
Type IIA topoisomerases together manage chromosome integrity and topology in cells. Topoisomerase II (called gyrase in bacteria) primarily introduces negative supercoils into DNA. In bacteria, topoisomerase II consists of two polypeptide subunits, gyrA and gyrB, which form a heterotetramer: (BA)2. In most eukaryotes, topoisomerase II consists of a single polypeptide, where the N- and C-terminal regions correspond to gyrB and gyrA, respectively; this topoisomerase II forms a homodimer that is equivalent to the bacterial heterotetramer. There are four functional domains in topoisomerase II: domain 1 (N-terminal of gyrB) is an ATPase, domain 2 (C-terminal of gyrB) is responsible for subunit interactions, domain 3 (N-terminal of gyrA) is responsible for the breaking-rejoining function through its capacity to form protein-DNA bridges, and domain 4 (C-terminal of gyrA) is able to non-specifically bind DNA [PUBMED:8982450].
Topoisomerase IV primarily decatenates DNA and relaxes positive supercoils, which is important in bacteria, where the circular chromosome becomes catenated, or linked, during replication [PUBMED:16023670]. Topoisomerase IV consists of two polypeptide subunits, parE and parC, where parC is homologous to gyrA and parE is homologous to gyrB.
This entry represents the C-terminal region (C-terminal part of domain 2) of subunit B found in topoisomerase II (gyrB) and topoisomerase IV (parE), which are primarily of bacterial origin. It does not include the topoisomerase II enzymes composed of a single polypeptide, as are found in most eukaryotes. This region is involved in subunit interaction, which accounts for the difference between subunit B and single polypeptide topoisomerase II.
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)|
|ATP binding (GO:0005524)|
|DNA topoisomerase (ATP-hydrolyzing) activity (GO:0003918)|
|Biological process||DNA topological change (GO:0006265)|
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Curation and family details
|Seed source:||Pfam-B_332 (release 3.0)|
|Author:||Finn RD, Bateman A|
|Number in seed:||72|
|Number in full:||9044|
|Average length of the domain:||62.90 aa|
|Average identity of full alignment:||53 %|
|Average coverage of the sequence by the domain:||9.63 %|
|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:||16|
|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 DNA_gyraseB_C domain has been found. There are 38 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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