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Related Concept Videos

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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Restarting Stalled Replication Forks02:37

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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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DNA Helicases00:55

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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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DNA Replication02:40

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DNA replication involves the separation of the two strands of the double helix, with each strand serving as a template from which the new complementary strand is copied.  After replication, each double-stranded DNA includes one parental or “old” strand and one “new” strand. This is known as semiconservative replication. The resulting DNA molecules have the same sequence and are divided equally into the two daughter cells.
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Direct Restart of a Replication Fork Stalled by a Head-On RNA Polymerase
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The ring-shaped hexameric helicases that function at DNA replication forks.

Michael E O'Donnell1, Huilin Li2

  • 1Department of DNA Replication, Rockefeller University and HHMI, New York, NY, USA. odonnel@rockefeller.edu.

Nature Structural & Molecular Biology
|January 31, 2018
PubMed
Summary
This summary is machine-generated.

Hexameric helicases unwind DNA for replication across life. Despite no evolutionary link, bacterial and eukaryotic helicases share key features but also show surprising differences.

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Area of Science:

  • Molecular Biology
  • Biochemistry
  • Structural Biology

Background:

  • DNA replication necessitates duplex DNA strand separation.
  • Hexameric ring-shaped helicases perform this essential function in all domains of life.
  • Understanding these molecular machines is crucial for comprehending genome duplication.

Purpose of the Study:

  • To review recent studies on bacterial and archaeal/eukaryotic hexameric helicases.
  • To highlight shared fundamental features and unexpected distinctions between these two groups.
  • To provide a focused perspective on helicase structure and chemomechanical action.

Main Methods:

  • Literature review of recent structural and biochemical studies.
  • Comparative analysis of hexameric helicases from bacteria versus archaea/eukaryotes.
  • Focus on structure-function relationships and chemomechanical mechanisms.

Main Results:

  • Hexameric helicases, despite lacking evolutionary relatedness, exhibit conserved functional principles.
  • Significant structural and mechanistic distinctions exist between bacterial and archaeal/eukaryotic helicases.
  • Recent research is increasingly clarifying the detailed operations of these enzymes.

Conclusions:

  • Hexameric helicases are vital for DNA replication, with conserved yet distinct evolutionary paths.
  • Comparative studies reveal fundamental insights into enzyme mechanism and adaptation.
  • Further research promises to deepen our understanding of these essential molecular machines.