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Related Concept Videos

DNA Helicases00:55

DNA Helicases

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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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The Replisome03:01

The Replisome

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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...
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Restarting Stalled Replication Forks02:37

Restarting Stalled Replication Forks

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DNA replication is initiated at sites containing predefined DNA sequences known as origins of replication. DNA is unwound at these sites by the minichromosome maintenance (MCM) helicase and other factors such as Cdc45 and the associated GINS complex.The unwound single strands are protected by replication protein A (RPA) until DNA polymerase starts synthesizing DNA at the 5’ end of the strand in the same direction as the replication fork. To prevent the replication fork from falling apart,...
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Single-Strand DNA Binding Proteins01:03

Single-Strand DNA Binding Proteins

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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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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.
Types and Mechanism of action
Topoisomerases are divided into two main types. ...
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The DNA Replication Fork01:02

The DNA Replication Fork

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An organism’s genome needs to be duplicated in an efficient and error-free manner for its growth and survival. The replication fork is a Y-shaped active region where two strands of DNA are separated and replicated continuously. The coupling of DNA unzipping and complementary strand synthesis is a characteristic feature of a replication fork.   Organisms with small circular DNA, such as E. coli, often have a single origin of replication; therefore, they have only two replication...
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Related Experiment Video

Updated: Jun 10, 2025

Author Spotlight: Investigating the Motion Dynamics of the Eukaryotic Replisome Components at the Single-Molecule Level
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Author Spotlight: Investigating the Motion Dynamics of the Eukaryotic Replisome Components at the Single-Molecule Level

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Single-molecule insights into repetitive helicases.

Ya-Mei Zhang1, Bo Li1, Wen-Qiang Wu1

  • 1School of Nursing and Health, School of Life Sciences, State Key Laboratory of Crop Stress Adaptation and Improvement, Kaifeng Key Laboratory Active Prevention and Nursing of Alzheimer's Disease, Henan University, Kaifeng, China.

The Journal of Biological Chemistry
|October 18, 2024
PubMed
Summary

This review summarizes repetitive helicase motion, a newly discovered feature of these essential molecular motors. Understanding repetitive helicase mechanisms is crucial for nucleic acid metabolism and medical applications.

Keywords:
DNA helicaseRNA helicaserepetitive functionrepetitive motionsingle-molecule biophysics

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Author Spotlight: Unraveling the Dynamics of Eukaryotic DNA Replication Through Single-Molecule Visualization
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Direct Observation of Enzymes Replicating DNA Using a Single-molecule DNA Stretching Assay
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Area of Science:

  • Biochemistry
  • Molecular Biology
  • Structural Biology

Background:

  • Helicases are vital enzymes for nucleic acid metabolism, essential for fundamental biological processes.
  • Studying helicases is medically important due to their roles in various diseases.
  • Single-molecule techniques offer unprecedented insights into helicase dynamics, overcoming limitations of bulk assays.

Purpose of the Study:

  • To review and summarize the phenomenon of repetitive motion in helicases.
  • To compare different types of repetitive helicase behaviors.
  • To discuss the molecular mechanisms underlying repetitive helicase activity.

Main Methods:

  • Literature review focusing on single-molecule studies of helicases.
  • Comparative analysis of reported helicase biochemical properties (rate, directionality, processivity, step size).
  • In-depth discussion of proposed molecular mechanisms for repetitive motion.

Main Results:

  • Single-molecule studies have revealed diverse biochemical properties of helicases.
  • Repetitive motion has emerged as a significant and previously unrecognized feature of some helicases.
  • Distinct patterns and mechanisms of repetitive motion have been observed across different helicases.

Conclusions:

  • Repetitive motion represents a key mechanistic insight into helicase function.
  • A systematic understanding of repetitive helicases is needed to elucidate their cellular roles.
  • This review provides a foundation for future research into the functional significance of repetitive helicase activity.