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Selection-dependent and Independent Generation of CRISPR/Cas9-mediated Gene Knockouts in Mammalian Cells
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Facilitation of CRISPR adaptation.

Stephen T Abedon1

  • 1Department of Microbiology; The Ohio State University; Mansfield, OH USA.

Bacteriophage
|December 14, 2011
PubMed
Summary
This summary is machine-generated.

CRISPR systems, bacterial defenses against phages, involve facilitation, adaptation, and interference. Facilitation, the survival of naive bacteria upon first phage exposure, suggests CRISPR may play a secondary defense role.

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Area of Science:

  • Microbiology
  • Immunology
  • Genetics

Background:

  • CRISPR systems function as adaptive immune systems in bacteria and archaea.
  • These systems defend against invading mobile genetic elements, primarily bacteriophages.
  • CRISPR functioning involves distinct sequential steps: facilitation, adaptation, and interference.

Purpose of the Study:

  • To analyze the "facilitation" step in CRISPR-Cas immune system functioning.
  • To evaluate the implications of the facilitation requirement for CRISPR's role as a bacterial defense mechanism.
  • To draw parallels between CRISPR functioning and vertebrate adaptive immunity.

Main Methods:

  • Conceptual analysis and synthesis of existing research on CRISPR-Cas systems.
  • Comparative analysis of CRISPR functioning with innate and adaptive immunity in vertebrates.
  • Examination of the sequential steps of CRISPR defense: facilitation, adaptation, and interference.

Main Results:

  • The "facilitation" step, where naive bacteria survive initial phage exposure, is crucial for subsequent adaptation (spacer acquisition).
  • The necessity of this pre-adaptation survival suggests CRISPR systems may not be the primary defense against highly virulent phages.
  • CRISPR's role, particularly the facilitation aspect, can be viewed as analogous to the development of adaptive immunity built upon innate immune mechanisms in vertebrates.

Conclusions:

  • CRISPR systems likely play a secondary role in bacterial defense, especially against virulent phages, due to the requirement for a facilitation step.
  • The facilitation step is essential for bacterial survival, enabling subsequent CRISPR adaptation and interference.
  • The functioning of CRISPR systems shares conceptual similarities with the layered defense strategies observed in vertebrate adaptive immunity.