What is the mechanism of topoisomerase?
DNA topoisomerases are classified according to their mechanism of action: type I enzymes cleave one DNA strand and pass single-stranded or double-stranded DNA through the break; type II enzymes cleave two DNA strands and pass a double strand through the break.
How does DNA topoisomerase work?
DNA topoisomerase-I works in the unwinding of double-stranded DNA. Here topoisomerase-I cuts one strand of DNA and allows another strand to pass through cut and rejoins the end. After completion of each topoisomerase-I activity, double-stranded DNA unwinds and linking the number of DNA is changed in a single step.
Which is the key function of DNA topoisomerase?
Abstract DNA topoisomerases solve the topological problems associated with DNA replication, transcription, recombination, and chromatin remodeling by introducing temporary single- or double-strand breaks in the DNA.
What is the function of topoisomerase 2?
Type II topoisomerases change DNA topology by generating transient DNA double strand breaks and are essential for all eukaryotic cells. Mammalian cells have two topoisomerase II (TOP2) isoforms, TOP2α and TOP2β. TOP2α is essential for all cells, and is essential for separating replicated chromosomes.
What is the difference between topoisomerase I and II?
Topoisomerase I and II are methods of dealing with supercoiled DNA. Topoisomerase I cuts one strand in the double-stranded DNA and no ATP is required for its function. On the other hand Topoisomerase, II cuts both strands in DNA and needs ATP for its activity. This is the key difference between Topoisomerase I and II.
What removes supercoiling?
Type II topoisomerases change DNA topology by breaking and rejoining double-stranded DNA. These enzymes can introduce or remove supercoils and can separate two DNA duplexes that are intertwined (see Figure 12-16).
What is the function of DNA gyrase?
DNA gyrase is an essential bacterial enzyme that catalyzes the ATP-dependent negative super-coiling of double-stranded closed-circular DNA. Gyrase belongs to a class of enzymes known as topoisomerases that are involved in the control of topological transitions of DNA.
Do humans have topoisomerase II?
On the basis of amino acid sequence comparisons between the two human topoisomerase II isoforms, as well as studies on bacterial and viral type II enzymes [59–61,65], it has been proposed that the ability to discern the geometry of DNA supercoils during relaxation resides in the C-terminal domain of human topoisomerase …
What is the function of topoisomerase II?
EC no. Type II topoisomerases are topoisomerases that cut both strands of the DNA helix simultaneously in order to manage DNA tangles and supercoils. They use the hydrolysis of ATP, unlike Type I topoisomerase. In this process, these enzymes change the linking number of circular DNA by ±2.
What does DNA topoisomerases, type II, bacterial mean?
DNA gyrase is a bacterial topoisomerase that introduces negative supercoils into DNA . Because it cuts both strands of DNA, it is considered to be a Class II topoisomerase. Type II topoisomerases are divided into two subfamilies: IIA and IIB.
What does DNA topoisomerase IV mean?
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.
What is the function of topoisomerase?
The overall function of DNA topoisomerase is to manage the topological state of the DNA in the cell. There are two types or families of this enzyme; type I family and type II family. Type I family passes one strand of the DNA through a break in the opposing strand. In other words, DNA topoisomerase type I enzyme cleaves only one strand of DNA.
What is the role of topoisomerase?
What is Topoisomerase. Topoisomerase is an enzyme responsible for the addition or removal of supercoils from the DNA duplex during DNA replication, transcription, chromatin remodelling, and recombination. It introduces single- or double-strand breaks to the DNA molecule.