Related Experiment Video
Updated: Jun 14, 2025
11:53
Substrate Generation for Endonucleases of CRISPR/Cas Systems
Published on: September 8, 2012
27.3K
Diverse viral cas genes antagonize CRISPR immunity
Mark A Katz1, Edith M Sawyer1, Luke Oriolt1
1Department of Microbiology, University of Washington, Seattle, WA, USA.
Nature
|September 4, 2024
Summary
Researchers discovered new anti-CRISPR (Acr) proteins in Listeria that target bacterial CRISPR-Cas immune systems. These Acrs evolve from Cas genes, offering broad-spectrum control over genome editing technologies.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Prokaryotic CRISPR-Cas systems provide adaptive immunity against phages and plasmids.
- Anti-CRISPR proteins (Acrs) counteract CRISPR-Cas immunity by inhibiting Cas protein activity.
- The evolutionary origins and broad-spectrum inhibition mechanisms of Acrs remain largely unknown.
Purpose of the Study:
- Investigate Acr content and inhibition specificity in diverse Listeria isolates.
- Identify novel Acr gene families and their origins.
- Explore the evolution of Acrs through cas gene co-option.
Main Methods:
- Analysis of CRISPR-Cas systems in Listeria isolates.
- Identification and characterization of novel acr gene families.
- Probing viral sequence databases for orphan cas genes.
- Functional verification of identified Acrs and cas homologues.
Main Results:
- Discovered 11 new and 4 known acr gene families in Listeria, encoded by mobile elements.
- Identified two Acrs with homology to type I-B Cas proteins, one forming a defective interference complex.
- Found a type I-B Cas homologue inhibiting RNA-targeting type VI CRISPR via crRNA degradation.
- Verified a broad-spectrum cas3 homologue inhibiting types I-B, II-A, and VI-A CRISPR immunity.
Conclusions:
- Provided direct evidence for Acr evolution through cas gene co-option.
- Identified novel Acrs with potential for broad-spectrum control of genome editing technologies.
- Expanded understanding of CRISPR-Cas system subversion and evolution.
Related Concept Videos
02:53CRISPR and crRNAs
16.9K
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...
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...
16.9K
01:59CRISPR
49.9K
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...
49.9K
02:31Homologous Recombination
50.3K
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...
50.3K
00:36Viral Mutations
32.2K
A mutation is a change in the sequence of bases of DNA or RNA in a genome. Some mutations occur during replication of the genome due to errors made by the polymerase enzymes that replicate DNA or RNA. Unlike DNA polymerase, RNA polymerase is prone to errors because it is not capable of “proofreading” its work. Viruses with RNA-based genomes, like HIV, therefore accrue mutations faster than viruses with DNA-based genomes. Because mutation and recombination provide the raw material...
32.2K
00:57Viral Recombination
23.3K
Cells are sometimes infected by more than one virus at once. When two viruses disassemble to expose their genomes for replication in the same cell, similar regions of their genomes can pair together and exchange sequences in a process called recombination. Alternatively, viruses with segmented genomes can swap segments in a process called reassortment.
23.3K
01:29Immune Response Against Viral Pathogens
765
The immune system's response to viral infections is a complex and coordinated process involving natural killer (NK) cells, T cell-mediated responses, and antibody-mediated responses.
NK Cells
NK cells are a crucial part of our innate immune system, acting as the first line of defense against viral infections. These cells can recognize and kill infected cells without prior exposure to the virus, effectively slowing down the spread of infection. Additionally, NK cells produce proinflammatory...
NK Cells
NK cells are a crucial part of our innate immune system, acting as the first line of defense against viral infections. These cells can recognize and kill infected cells without prior exposure to the virus, effectively slowing down the spread of infection. Additionally, NK cells produce proinflammatory...
765