Topoisomerase IV

Topoisomerase IV is one of two type-II topoisomerases in bacteria, the other being DNA gyrase. Like gyrase, topoisomerase IV is able to pass one double-strand of DNA through another double-strand of DNA, thereby changing the linking number of DNA by two in each enzymatic step.

Functions

Topoisomerase IV has two functions in the cell.

• First, it is responsible for unlinking, or decatenating, DNA following DNA replication. The double-helical nature of DNA and its semiconservative mode of replication causes the two newly replicated DNA strands to be interlinked. These links must be removed in order for the chromosome (and plasmids) to segregate into daughter cells so that cell division can complete.

• Topoisomerase IV's second function in the cell is to relax positive supercoils. It shares this role with DNA gyrase, which is also able to relax positive supercoils. Together, gyrase and topoisomerase IV remove the positive supercoils that accumulate ahead of a translocating DNA polymerase, allowing DNA replication to continue unhindered by topological strain.

• DNA gyrases are analogous enzymes in other organisms.

Clinical significance

Topoisomerase IV is also a target of antibiotics, such as the quinolone drugs, which include ciprofloxacin.

External links

• MeSH DNA+Topoisomerase+IV

This enzyme-related article is a stub. You can help Wikipedia by expanding it.v · Categories: EC 5.99.1 Enzyme stubs Wikimedia Foundation. 2010. Игры ⚽ Нужен реферат? National Union Attack Mézières-en-Brenne Look at other dictionaries: topoisomerase II — topoisomerase II. = DNA gyrase (см.). (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь. Topoisomerase — Topoisomerases (type I: EC 5.99.1.2, type II: EC 5.99.1.3) are enzymes that regulate the overwinding or underwinding of DNA. The winding problem of DNA arises due to the intertwined nature of its double helical structure. For example, during DNA… …   Wikipedia Topoisomerase — Topoisomerasen Bezeichner Externe IDs CAS Nummer …   Deutsch Wikipedia Topoisomerase I — Topoisomerasen Typ I Topoisomerase an DNA …   Deutsch Wikipedia Topoisomerase II — ADN topoïsomérase Les ADN topoïsomérases (de type I : ADN topo isomérases et de type II : ADN gyrases) sont des enzymes qui contrôlent la structure topologique de l’ADN en générant des coupures transitoires dans celui ci et en… …   Wikipédia en Français Topoisomérase — ADN topoïsomérase Les ADN topoïsomérases (de type I : ADN topo isomérases et de type II : ADN gyrases) sont des enzymes qui contrôlent la structure topologique de l’ADN en générant des coupures transitoires dans celui ci et en… …   Wikipédia en Français Topoisomérase II — ADN topoïsomérase Les ADN topoïsomérases (de type I : ADN topo isomérases et de type II : ADN gyrases) sont des enzymes qui contrôlent la structure topologique de l’ADN en générant des coupures transitoires dans celui ci et en… …   Wikipédia en Français Topoisomerase II — Topoisomerasen TypII Bezeichner Externe IDs CAS Num …   Deutsch Wikipedia topoisomerase — topoizomerazė statusas T sritis chemija apibrėžtis Fermentas, katalizuojantis ciklinės DNR struktūrinius pokyčius. atitikmenys: angl. topoisomerase rus. топоизомераза …   Chemijos terminų aiškinamasis žodynas Topoisomerase inhibitor — Topoisomerase inhibitors are agents designed to interfere with the action of topoisomerase enzymescite web |url=http://www.cancer.gov/Templates/db alpha.aspx?CdrID=46665 |title=Definition of topoisomerase inhibitor NCI Dictionary of Cancer Terms… …   Wikipedia 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”