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Related Concept Videos

CRISPR/Cas9 Genome Editing01:28

CRISPR/Cas9 Genome Editing

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The CRISPR-Cas system serves as a bacterial defense mechanism against invading genetic elements such as viruses and plasmids, forming the foundation for its adaptation as a powerful genome-editing tool. Originally discovered in prokaryotes, this system has been repurposed to revolutionize genetic engineering across a wide range of organisms, including plants, animals, and humans. The core component, Cas9, is an endonuclease derived from Streptococcus pyogenes, capable of introducing...
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The Antiviral System of Bacteria and Archaea: CRISPR01:23

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CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats is a adaptive immune system found in bacteria and archaea that protects against viral infections. This system enables prokaryotic cells to identify, remember, and neutralize foreign genetic elements, primarily bacteriophages, by storing fragments of the invader’s DNA as a genetic memory.The CRISPR immune response begins during an initial infection. Cas (CRISPR-associated) proteins play a central role in this...
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CRISPR and crRNAs02:53

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Bacteria and archaea are susceptible to viral infections just like eukaryotes; therefore, they have developed a unique adaptive immune system to protect themselves. Clustered regularly interspaced short palindromic repeats and CRISPR-associated proteins (CRISPR-Cas) are present in more than 45% of known bacteria and 90% of known archaea.
The CRISPR-Cas system stores a copy of foreign DNA in the host genome and uses it to identify the foreign DNA upon reinfection. CRISPR-Cas has three different...
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Genome editing technologies allow scientists to modify an organism’s DNA via the addition, removal, or rearrangement of genetic material at specific genomic locations. These types of techniques could potentially be used to cure genetic disorders such as hemophilia and sickle cell anemia. One popular and widely used DNA-editing research tool that could lead to safe and effective cures for genetic disorders is the CRISPR-Cas9 system. CRISPR-Cas9 stands for Clustered Regularly Interspaced...
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The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
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Caspases01:24

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Caspase, a family of cysteine proteases, serve as effectors in apoptosis. The ced3 gene in C.elegans was first identified to be involved in apoptosis. This gene encodes the ced-3 caspase that is similar to the interleukin-1-beta converting enzyme or ICE in mammals. In addition to apoptosis, caspases also function in the inflammatory response. Inflammatory caspases are essential in activating pro-inflammatory cytokines that recruit immune cells and block the replication of pathogens inside...
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Related Experiment Video

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Author Spotlight: Establishing CENP-E Knockout HeLa Cells &#8211; A Novel Approach to Study Kinesin-7 CENP-E Biology and its Inhibitors
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CRISPR-Cas immunity in prokaryotes.

Luciano A Marraffini1

  • 1Laboratory of Bacteriology, The Rockefeller University, 1230 York Avenue, New York, New York 10065, USA.

Nature
|October 4, 2015
PubMed
Summary

Prokaryotic cells use clustered regularly interspaced short palindromic repeat (CRISPR)-Cas systems for adaptive immunity against viruses. This system integrates viral DNA sequences to guide targeted DNA cleavage, providing heritable resistance.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Genetics

Background:

  • Prokaryotic organisms face constant threats from viruses (bacteriophages).
  • Various defense mechanisms have evolved in prokaryotes to combat viral infections.
  • Clustered regularly interspaced short palindromic repeat (CRISPR)-Cas systems are unique among these defenses, offering adaptive immunity.

Purpose of the Study:

  • To explain the mechanism of adaptive immunity in prokaryotes via CRISPR-Cas systems.
  • To highlight the role of spacer acquisition in host defense and evolution.
  • To describe how CRISPR-Cas mediated immunity is passed to progeny.

Main Methods:

  • The study focuses on the molecular mechanisms of CRISPR-Cas systems.
  • It describes the process of spacer acquisition from foreign genetic material.

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  • It explains the transcription of spacers into RNA guides and their role in DNA targeting.

    • Main Results:

    • CRISPR-Cas systems provide adaptive immunity by integrating viral DNA fragments (spacers) into the host genome.
    • These spacers generate RNA guides that direct Cas nucleases to cleave invading viral DNA.
    • This process confers resistance to the host cell and its descendants.

    Conclusions:

    • CRISPR-Cas systems represent a sophisticated adaptive immune system in prokaryotes.
    • Spacer acquisition allows for rapid, heritable resistance to specific viral threats.
    • This mechanism drives a unique form of evolutionary adaptation in microbial populations.