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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

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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...
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.

Katherine Evans-Roberts, Anthony Maxwell

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    Summary
    This summary is machine-generated.

    DNA topoisomerases are essential enzymes regulating DNA topology, crucial for replication and transcription. Recent structural studies reveal their mechanisms and drug targets, aiding antibacterial and anticancer agent development.

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    Area of Science:

    • Biochemistry
    • Molecular Biology
    • Enzymology

    Background:

    • DNA topoisomerases are vital enzymes controlling DNA topology, essential for replication and transcription in all cells.
    • These enzymes are classified into Type I and Type II, with further subclassifications (IA, IB, IC, IIA, IIB) based on structural and mechanistic differences.
    • Topoisomerases function by stabilizing transient DNA breaks through tyrosyl-phosphate covalent intermediates.

    Purpose of the Study:

    • To review the fundamental characteristics of DNA topoisomerases, with a primary focus on prokaryotic enzymes.
    • To elucidate recent structural advancements providing novel insights into topoisomerase mechanisms.
    • To explore the molecular basis underlying the efficacy of topoisomerase-specific drugs.

    Main Methods:

    • Review of existing literature on DNA topoisomerase structure and function.
    • Analysis of recent crystallographic and biochemical studies on prokaryotic topoisomerases.
    • Examination of structure-activity relationships for topoisomerase inhibitors.

    Main Results:

    • Detailed overview of Type I and Type II topoisomerase classifications and their enzymatic mechanisms.
    • Highlighting key structural insights into DNA binding, cleavage, and religation activities.
    • Identification of conserved structural features relevant to drug targeting.

    Conclusions:

    • DNA topoisomerases are indispensable enzymes with critical roles in DNA metabolism.
    • Structural biology has significantly advanced our understanding of topoisomerase function and drug interactions.
    • Prokaryotic topoisomerases represent validated targets for developing novel antibacterial and anticancer therapies.