TOP3A
TOP3A (DNA topoisomerase III alpha, also known as ZGRF7 or TOP3) is a type IA topoisomerase that relieves torsional tension in DNA by transiently cleaving and rejoining a single strand. It also acts in chromosome separation, recombination control and mitochondrial DNA segregation. Browse Assay Genie's current range of TOP3A research reagents below, or read on for the biology behind the target.
TOP3A releases the supercoiling and torsional tension introduced into DNA during replication and transcription. It does so by introducing a single-strand break through transesterification at a target site in duplex DNA. The catalytic tyrosine of the enzyme attacks the scissile phosphodiester, forming a DNA-(5'-phosphotyrosyl)-enzyme intermediate and releasing a 3'-OH DNA strand. The free strand then passes around the unbroken strand, removing supercoils, and in the religation step the 3'-OH attacks the covalent intermediate, expelling the active-site tyrosine and restoring the phosphodiester backbone.
The enzyme has DNA decatenation activity and is an essential component of the RMI complex, where it contributes to chromosome separation and the processing of homologous recombination intermediates, limiting DNA crossover formation. The NCBI Gene summary also describes a complex with BLM that regulates recombination in somatic cells. In mitochondria, TOP3A is required for mtDNA decatenation and segregation after replication is complete, a process that does not require BLM, RMI1 or RMI2. UniProt reports the protein in the mitochondrion matrix.
TOP3A belongs to the type IA topoisomerase family and is classed by HGNC within the zinc fingers GRF-type and topoisomerases gene groups. The TOP3A gene undergoes alternative splicing, giving multiple transcript variants that encode different isoforms. The mouse ortholog is Top3a. Previous HGNC naming was topoisomerase (DNA) III alpha, and the symbols ZGRF7 and TOP3 are also used in the literature.
TOP3A relieves supercoiling and torsional stress generated during replication and transcription, making it a model type IA topoisomerase for studying DNA topology.
As part of the RMI complex and its association with BLM, TOP3A helps process recombination intermediates and limit crossover formation.
TOP3A decatenates DNA and contributes to chromosome separation, so it is relevant to studies of how linked DNA molecules are resolved.
TOP3A is required for mtDNA decatenation and segregation after replication, linking it to mitochondrial genome maintenance.
TOP3A is a type IA topoisomerase that transiently cleaves and rejoins one strand of the DNA duplex, releasing supercoiling and torsional tension from replication and transcription. It also decatenates DNA, works in the RMI complex during chromosome separation and is required for mitochondrial DNA segregation.
TOP3A is the HGNC symbol for DNA topoisomerase III alpha, also called DNA topoisomerase 3-alpha. Aliases include ZGRF7 and TOP3, and an earlier name was topoisomerase (DNA) III alpha. Alternative splicing produces several transcript variants that encode different isoforms.
A mouse ortholog, Top3a, is recorded for this gene. TOP3A belongs to the type IA topoisomerase family. Check the datasheet of any product for its validated reactivity before using it with a particular species.
Other DNA topoisomerases that control DNA topology during replication and transcription.
Gene and protein annotations from HGNC, NCBI Gene and UniProt Q13472; product specifications from Assay Genie datasheets.