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Related Concept Videos

Replication in Eukaryotes02:31

Replication in Eukaryotes

Overview
DNA Helicases00:55

DNA Helicases

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...
The Replisome03:01

The Replisome

DNA replication is carried out by a large complex of proteins that act in a coordinated matter to achieve high-fidelity DNA replication. Together this complex is known as the DNA replication machinery or the replisome.
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with the...
DNA Topoisomerases02:02

DNA Topoisomerases

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.  Type I...
The Replisome03:01

The Replisome

DNA replication is carried out by a large complex of proteins that act in a coordinated matter to achieve high-fidelity DNA replication. Together this complex is known as the DNA replication machinery or the replisome.
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with the...
Replication in Eukaryotes01:29

Replication in Eukaryotes

In eukaryotic cells, DNA replication is highly conserved and tightly regulated. Multiple linear chromosomes must be duplicated with high fidelity before cell division, so there are many proteins that fulfill specialized roles in the replication process. Replication occurs in three phases: initiation, elongation, and termination, and ends with two complete sets of chromosomes in the nucleus.
Many Proteins Orchestrate Replication at the Origin
Eukaryotic replication follows many of the same...

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Related Experiment Video

Updated: Jun 24, 2026

Direct Observation of Enzymes Replicating DNA Using a Single-molecule DNA Stretching Assay
17:03

Direct Observation of Enzymes Replicating DNA Using a Single-molecule DNA Stretching Assay

Published on: March 24, 2010

Enzymes that push DNA around.

J L Keck, J M Berger

    Nature Structural Biology
    |October 3, 1999
    PubMed
    Summary
    This summary is machine-generated.

    DNA topoisomerases control DNA structure by breaking and rejoining DNA strands. New research reveals the conformational states of E. coli topoisomerase, improving our understanding of DNA recognition and supercoil relaxation.

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    A Simple, Robust, and High Throughput Single Molecule Flow Stretching Assay Implementation for Studying Transport of Molecules Along DNA
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    Area of Science:

    • Biochemistry
    • Molecular Biology
    • Structural Biology

    Background:

    • DNA topoisomerases are essential enzymes that manage DNA topology.
    • These enzymes utilize cycles of DNA cleavage, manipulation, and religation.
    • Understanding their mechanisms is crucial for cellular processes.

    Discussion:

    • Two recent studies detail diverse protein conformations and nucleotide-protein complexes of Escherichia coli topoisomerase.
    • These findings offer a dynamic view of the enzyme's functional states.
    • Analysis focuses on the enzyme's interaction with DNA and its catalytic activity.

    Key Insights:

    • The research elucidates the structural basis for DNA recognition by topoisomerases.
    • New insights into the catalytic mechanism of supercoil relaxation have been uncovered.
    • The study highlights the importance of conformational flexibility in enzyme function.

    Outlook:

    • Further investigation into topoisomerase conformational dynamics could reveal novel therapeutic targets.
    • Understanding these mechanisms may aid in the development of new drugs targeting DNA topology.
    • Comparative studies across different topoisomerase families could broaden our understanding.