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Related Concept Videos

Inhibitors of Bacterial DNA Synthesis01:28

Inhibitors of Bacterial DNA Synthesis

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Bacterial pathogens depend on precise and efficient DNA replication to sustain infection. Two type II topoisomerases—DNA gyrase and topoisomerase IV—are critical to this process, as they resolve DNA supercoiling and unlink chromosomes during replication. Fluoroquinolones, synthetic derivatives of quinolones, exploit this mechanism by stabilizing the transient DNA–enzyme cleavage complex, preventing strand religation, and causing lethal double-strand breaks. These...
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DNA Topoisomerases02:02

DNA Topoisomerases

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Topoisomerases are enzymes that relax overwound DNA molecules during various cell processes, including DNA replication and transcription. These enzymes regulate positive and negative DNA supercoiling without changing the nucleotide sequence. DNA overwinding in a clockwise direction results in positively supercoiled DNA, whereas underwinding in a counterclockwise direction produces negatively supercoiled DNA.
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DNA unwinding helicase enzymes are a type of motor protein. Motor proteins can translocate along filaments or polymers using energy generated from ATP hydrolysis. Helicases are involved in all the important cellular processes where DNA unwinding is required, such as DNA replication, repair, recombination, and transcription. They are present in all living organisms, but vary in their structure, function, and mechanism of action. For example, in prokaryotes, DnaB helicase binds and translocates...
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For successful DNA replication, the unwinding of double-stranded DNA must be accompanied by stabilization and protection of the separated single strands of the DNA. This crucial task is performed by single-strand DNA-binding (SSB) proteins. They bind to the DNA in a sequence-independent manner, which means that the nitrogenous bases of the DNA need not be present in a specific order for binding of SSB proteins to it. The binding of SSB proteins straightens single-stranded DNA (ssDNA) and makes...
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Translesion (TLS) polymerases rescue stalled DNA polymerases at sites of damaged bases by replacing the replicative polymerase and installing a nucleotide across the damaged site. Doing so, TLS allows additional time for the cell to repair the damage before resuming regular DNA replication.
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The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
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DNA topoisomerases.

T S Hsieh1

  • 1Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710.

Current Opinion in Cell Biology
|June 1, 1992
PubMed
Summary
This summary is machine-generated.

DNA topoisomerases are crucial enzymes that regulate DNA structure and impact chromosome functions. Ongoing research explores their specific roles in chromosome condensation, decondensation, and segregation.

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Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • DNA topoisomerases are essential enzymes that manage DNA topology within cells.
  • These enzymes are critical for various DNA-related processes, including replication, transcription, and repair.

Purpose of the Study:

  • To investigate the distinct and critical functions of multiple DNA topoisomerases.
  • To elucidate the roles of DNA topoisomerases in chromosome condensation, decondensation, and segregation.

Main Methods:

  • Utilizing advanced molecular biology techniques.
  • Employing genetic manipulation and biochemical assays.

Main Results:

  • Identifying specific functions of different topoisomerase enzymes.
  • Demonstrating the involvement of topoisomerases in dynamic chromosome structure changes.

Conclusions:

  • DNA topoisomerases play multifaceted roles in maintaining genome stability.
  • Further research into topoisomerase mechanisms can reveal new therapeutic targets.