What does type II topoisomerase do?

What does type II topoisomerase do?

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).

Is topoisomerase the same as DNA gyrase?

DNA gyrase and topoisomerase IV are the two type II topoisomerases present in bacteria. Gyrase is involved primarily in supporting nascent chain elongation during replication of the chromosome, whereas topoisomerase IV separates the topologically linked daughter chromosomes during the terminal stage of DNA replication.

What does the word topoisomerase mean?

: any of a class of enzymes that reduce supercoiling in DNA by breaking and rejoining one or both strands of the DNA molecule.

What does DNA topoisomerase gyrase do?

DNA gyrase (topoisomerase II) and the other topoisomerases (I and III) play a crucial role in maintaining the nucleoid structure and the compact supercoiled domains of the chromosome. These enzymes help with the winding and unwinding of the DNA that occurs during replication and transcription.

How do topoisomerase II inhibitors work?

Inhibitors of the mammalian enzymes are widely used antitumor drugs. They stabilize topoisomerase-DNA cleavable complexes by hindering the DNA relegating step of the catalytic reaction, thus resulting in DNA cleavage stimulation. Topoisomerase II inhibitors may also have genotoxic effects.

What is the job of topoisomerase?

Topoisomerase: A class of enzymes that alter the supercoiling of double-stranded DNA. (In supercoiling the DNA molecule coils up like a telephone cord, which shortens the molecule.) The topoisomerases act by transiently cutting one or both strands of the DNA.

What does a helicase do?

Helicases are enzymes that bind and may even remodel nucleic acid or nucleic acid protein complexes. There are DNA and RNA helicases. DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied.

Is helicase a topoisomerase?

Summary – Helicase vs Topoisomerase Helicase is an enzyme that separates annealed two strands of DNA, RNA or DNA-RNA hybrid by breaking hydrogen bonds between bases. In contrast, topoisomerase is an enzyme that creates single-stranded or double-stranded breaks to relieve stress during supercoiling.

What are the two types of topoisomerases?

Type II topoisomerases are divided into two subfamilies: IIA and IIB. In eukaryotes, IIA enzymes catalyze the relaxation of positively or negatively supercoiled DNA, as well as the decatenation and unknotting of DNA helices.

What’s the difference between Type IIa and IIB topoisomerases?

Type IIA topoisomerases form double-stranded breaks with four-base pair overhangs, while type IIB topoisomerases form double-stranded breaks with two base overhangs. In addition, type IIA topoisomerases are able to simplify DNA topology, while type IIB topoisomerases do not.

How are topoisomerases and DNA supercoils are similar?

Bacterial topoisomerases and human topoisomerases proceed via similar mechanisms for managing DNA supercoils. Topoisomerases can be further classified into subfamilies. In the type I family, there are two subfamilies; type IA and type IB when the enzyme links to the 5’ phosphate of the DNA strand, and the 3’ phosphate on the DNA, respectively.

What is the structure of topoisomerase II in yeast?

Structure of yeast topoisomerase II bound to a doubly nicked 34-mer duplex DNA (PDB ID =2RGR). The Toprim fold is colored cyan; the DNA is colored orange; the HTH is colored magenta; and the C-gate is colored purple. Notice that the DNA is bent by ~160 degrees through an invariant isoleucine (Ile833 in yeast).