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Related Concept Videos

DNA Topoisomerases02:02

DNA Topoisomerases

37.6K
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.
Types and Mechanism of action
Topoisomerases are divided into two main types. ...
37.6K
DNA Helicases00:55

DNA Helicases

25.0K
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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Inhibitors of Bacterial DNA Synthesis01:28

Inhibitors of Bacterial DNA Synthesis

51
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...
51
Single-Strand DNA Binding Proteins01:03

Single-Strand DNA Binding Proteins

17.2K
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...
17.2K
Translesion DNA Polymerases02:10

Translesion DNA Polymerases

11.8K
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.
TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...
11.8K
Homologous Recombination02:31

Homologous Recombination

65.6K
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.

Natassja G Bush, Katherine Evans-Roberts, Anthony Maxwell

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    PubMed
    Summary
    This summary is machine-generated.

    DNA topoisomerases are essential enzymes regulating DNA structure in all cells. Bacterial topoisomerases are key targets for developing novel antibacterial agents due to their crucial roles and drug-targeting potential.

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    Area of Science:

    • Biochemistry
    • Molecular Biology
    • Microbiology

    Background:

    • DNA topoisomerases are crucial enzymes that manage DNA topology in all living cells.
    • They are classified into two types (I and II) based on their mechanism of DNA strand breakage.
    • Bacterial DNA gyrase, a type II topoisomerase, uniquely introduces supercoils into DNA.

    Purpose of the Study:

    • To elucidate the structure and mechanism of DNA topoisomerases.
    • To describe the essential roles of topoisomerases within the bacterial cell.
    • To review the targeting of bacterial topoisomerases by antimicrobial agents.

    Main Methods:

    • Literature review of DNA topoisomerase structure and function.
    • Analysis of topoisomerase reaction mechanisms involving DNA strand passage.
    • Examination of existing and potential drug targets among bacterial topoisomerases.

    Main Results:

    • DNA topoisomerases control DNA topology through transient strand breaks and DNA segment passage.
    • All topoisomerases can relax DNA, while bacterial DNA gyrase can also introduce supercoiling.
    • Bacterial topoisomerases are essential for cell viability and represent validated targets for antibacterial drugs.

    Conclusions:

    • DNA topoisomerases are vital enzymes with distinct mechanisms and roles in DNA metabolism.
    • Their essentiality and mechanism of action make them attractive targets for therapeutic intervention.
    • Inhibitors of bacterial topoisomerases, including clinically used antibiotics, are effective antibacterial strategies.