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Related Concept Videos

Replication in Prokaryotes02:35

Replication in Prokaryotes

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Replication in Prokaryotes02:35

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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...
DNA Topoisomerases02:02

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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.
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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...
Replication in Prokaryotes01:32

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DNA replication has three main steps: initiation, elongation, and termination. Replication in prokaryotes begins when initiator proteins bind to the single origin of replication (ori) on the cell's circular chromosome. Replication then proceeds around the entire circle of the chromosome in each direction from the two replication forks, resulting in two DNA molecules.
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Tools to Study the Role of Architectural Protein HMGB1 in the Processing of Helix Distorting, Site-specific DNA Interstrand Crosslinks
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Published on: November 10, 2016

Bacterial helicases.

E H Egelman1

  • 1Department of Cell Biology and Neuroanatomy, University of Minnesota Medical School, Minneapolis, Minnesota, 55455, USA.

Journal of Structural Biology
|March 2, 1999
PubMed
Summary
This summary is machine-generated.

Escherichia coli possesses at least 12 helicases crucial for DNA and RNA processes. Despite a conserved catalytic core, these essential proteins exhibit significant functional diversity.

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Area of Science:

  • Molecular Biology
  • Biochemistry
  • Genetics

Background:

  • Helicases are ATP-dependent enzymes that unwind nucleic acid duplexes.
  • These proteins are vital for fundamental cellular processes including DNA replication, repair, recombination, and transcription.
  • Escherichia coli (E. coli) encodes a diverse set of at least 12 distinct helicases.

Purpose of the Study:

  • To explore the roles and diversity of helicases in Escherichia coli.
  • To highlight the structural conservation and functional divergence among E. coli helicases.

Main Methods:

  • Sequence analysis to identify and classify helicases.
  • Review of existing crystallographic and functional studies.

Main Results:

  • Identification of at least 12 helicase proteins in E. coli.
  • Revelation of a conserved catalytic core shared with RecA and F1-ATPase.
  • Evidence indicating substantial functional divergence among these helicases.

Conclusions:

  • E. coli utilizes a broad repertoire of helicases for various nucleic acid metabolism pathways.
  • Structural similarities suggest a common ancestry, while functional differences underscore specialized roles.