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6.7:

DNA Helicases

JoVE Core
Molecular Biology
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JoVE Core Molecular Biology
DNA Helicases

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The helicases involved in DNA replication are known as replicative helicases. They contain six subunits that surround a central pore large enough to allow single-stranded DNA to pass through. Helicase undergoes a conformational change In order to move along the DNA using the energy from ATP hydrolysis. Each of the six subunits of helicase has an ATP binding site with inherent ATPase activity, which is the ability to break down ATP to ADP and inorganic phosphate. As helicase breaks down ATP, the subunits move relative to each other causing DNA translocation. To begin unwinding DNA, helicase binds to a single strand of the DNA at the origin of the replication and slides along the selected strand of DNA.

6.7:

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 along the lagging strand template in the 5' to 3' direction. In eukaryotes, the minichromosome maintenance (MCM) protein complex is a DNA helicase that binds and translocates along the leading strand template in the 3' to 5' direction.

Helicases as Therapeutic Targets

Being an indispensable component of the DNA replication machinery, helicase is emerging as a new target for the development of drugs against bacterial and viral infections and for cancer treatment. Cancer cells are characterized by rapid proliferation, which demands a high DNA replication rate and a corresponding increase in the production of MCM helicase. Thus, inhibition or depletion of MCM helicase by the right drugs could suppress the rapid growth of cancer cells.

Suggested Reading

  1. Tuteja, Narendra, and Renu Tuteja. "Prokaryotic and eukaryotic DNA helicases: essential molecular motor proteins for cellular machinery." European Journal of Biochemistry 271, no. 10 (2004): 1835-1848. https://febs.onlinelibrary.wiley.com/doi/epdf/10.1111/j.1432-1033.2004.04093.x
  2. Seo, Yeon-Soo, and Young-Hoon Kang. "The human replicative helicase, the CMG complex, as a target for anti-cancer therapy." Frontiers in Molecular Biosciences 5 (2018): 26. https://www.frontiersin.org/articles/10.3389/fmolb.2018.00026/full