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Related Concept Videos

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

Single-Strand DNA Binding Proteins

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...
Cohesins02:20

Cohesins

Cohesin protein complexes are a molecular glue that holds two sister chromatids together. They play an important role both in mitosis and meiosis. In mitosis, all cohesin complexes present on the chromosomes are removed before the start of the anaphase stage.
Cohesin complexes in Meiotic Division
Meiosis involves two distinct rounds of chromosomal segregation and cell divisions— Meiosis I followed by Meiosis II – producing four daughter cells. Meiosis I includes the separation of homologous...
Cohesins02:20

Cohesins

Cohesin protein complexes are a molecular glue that holds two sister chromatids together. They play an important role both in mitosis and meiosis. In mitosis, all cohesin complexes present on the chromosomes are removed before the start of the anaphase stage.
Cohesin complexes in Meiotic Division
Meiosis involves two distinct rounds of chromosomal segregation and cell divisions— Meiosis I followed by Meiosis II – producing four daughter cells. Meiosis I includes the separation of homologous...
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...

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Hybrid Ensemble and Single-molecule Assay to Image the Motion of Fully Reconstituted CMG
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Hybrid Ensemble and Single-molecule Assay to Image the Motion of Fully Reconstituted CMG

Published on: July 26, 2024

Overview: what are helicases?

Colin G Wu1, Maria Spies

  • 1Department of Biochemistry, University of Iowa Carver College of Medicine, Iowa City, IA, USA.

Advances in Experimental Medicine and Biology
|November 20, 2012
PubMed
Summary
This summary is machine-generated.

DNA helicases, enzymes that unwind DNA, are crucial for DNA replication, repair, and recombination. Research reveals some helicases act as energy-dependent switches, expanding their known functions beyond strand separation.

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Tools to Study the Role of Architectural Protein HMGB1 in the Processing of Helix Distorting, Site-specific DNA Interstrand Crosslinks

Published on: November 10, 2016

Area of Science:

  • Molecular Biology
  • Biochemistry
  • Genetics

Background:

  • DNA helicases, discovered in the 1970s, were initially understood as enzymes catalyzing DNA strand separation using chemical energy.
  • These enzymes are vital for all DNA metabolic processes, including replication, recombination, and repair.
  • Defects in human helicases are associated with various genetic disorders, highlighting their biomedical significance.

Purpose of the Study:

  • To organize and update the understanding of DNA helicases.
  • To present evidence that not all helicases function solely as strand separators.
  • To introduce their roles as energy-dependent switches or translocases.

Main Methods:

  • Review of biochemical and structural features of DNA and its cellular organization.
  • Historical overview of helicase discovery, classification, structures, and mechanisms.
  • Highlighting key advances and ongoing research areas in helicase studies.

Main Results:

  • DNA helicases are ubiquitous enzymes involved in fundamental DNA processes.
  • Emerging evidence suggests some helicases function as energy-dependent switches or translocases, not just strand separators.
  • Helicase research is critical for understanding DNA metabolism and associated genetic disorders.

Conclusions:

  • The traditional view of DNA helicases needs updating to include their broader functional roles.
  • Continued research into helicase mechanisms and biomedical significance is essential.
  • This work provides a foundation for deeper exploration of helicase functions in subsequent chapters.