Why is topoisomerase necessary?

Topoisomerases catalyze and guide the unknotting or unlinking of DNA by creating transient breaks in the DNA using a conserved tyrosine as the catalytic residue. The insertion of (viral) DNA into chromosomes and other forms of recombination can also require the action of topoisomerases.

Do you need topoisomerase for transcription?

Topoisomerases are required during transcription to manage the DNA supercoiling that accumulates ahead and behind the transcription machinery56 (Fig. 2). Importantly, these studies showed that topoisomerase activity is required for transcription initiation but not for elongation or re-initiation.

What is the role of DNA topoisomerase in transcription?

Type IIA topoisomerases allow DNA double helical strands to pass through each other by generating transient DNA double strand breaks βDSBs), and in so doing, resolve torsional strain that accumulates during transcription, DNA replication, chromosome condensation, chromosome segregation and recombination.

What does topoisomerase do in bacteria?

Bacterial topoisomerase I is required for preventing hypernegative supercoiling of DNA during transcription. It plays an important role in transcription of stress genes during bacterial stress response.

What is the function of the enzyme topoisomerase in DNA replication mastering biology?

Topoisomerase breaks hydrogen bonds between the two parental strands. Topoisomerase breaks covalent bonds in the backbones of both parental strands. Single-strand binding proteins bind to the newly synthesized strand of DNA immediately after the DNA polymerase.

What does topoisomerase do in replication?

DNA topoisomerases unravel twists in DNA that occur as a result of DNA transcription and replication. The DNA topoisomerases I and II present in cells act through scission of the DNA backbone on one or two strands, respectively, followed by relief of torsional stress and then relegation of the broken DNA backbone.

Why is DNA gyrase topoisomerase necessary for replication?

Why is DNA gyrase necessary for replication? DNA synthesis relies on a single-stranded template; thus, double-stranded DNA molecules must be unwound prior to replication. DNA gyrase (also referred to as topoisomerase) reduces supercoiling (relaxes tension) which builds up during DNA unwinding, preventing DNA breakage.

What would happen if topoisomerase was unavailable for DNA replication How would this affect the process?

(a) If topoisomerase was not available for DNA replication the strands would not be able to relieve the tension created by helicase untwisting them. This may destabilize the strand and prevent binding and proper manipulation by other replication enzymes.

What happens when topoisomerase is inhibited?

Topoisomerase inhibitors block the ligation step of the cell cycle, which generates DNA single- and double-strand breaks, leading to apoptotic cell death.