CRISPR-based immunity can be employed to make these cultures more resistant to viral attack, which would otherwise impede productivity. The inherent functions of the CRISPR system are advantageous for industrial processes that utilize bacterial cultures. What are some applications of the CRISPR system? Creative applications of this primitive yet elegant defense system have emerged in disciplines as diverse as industry, basic research, and medicine. The specificity of CRISPR-based immunity in recognizing and destroying invading viruses is not just useful for bacteria. Because CRISPR RNA sequences are copied from the viral DNA sequences acquired during adaptation, they are exact matches to the viral genome and thus serve as excellent guides. Step 3) Targeting – CRISPR RNAs guide bacterial molecular machinery to destroy the viral material. This RNA chain is cut into short pieces called CRISPR RNAs. Unlike the double-chain helix structure of DNA, the resulting RNA is a single-chain molecule. Step 2) Production of CRISPR RNA – CRISPR repeats and spacers in the bacterial DNA undergo transcription, the process of copying DNA into RNA (ribonucleic acid). Step 1) Adaptation – DNA from an invading virus is processed into short segments that are inserted into the CRISPR sequence as new spacers. The CRISPR immune system works to protect bacteria from repeated viral attack via three basic steps :
If a previously unseen virus attacks, a new spacer is made and added to the chain of spacers and repeats. If another infection by the same virus should occur, the CRISPR defense system will cut up any viral DNA sequence matching the spacer sequence and thus protect the bacterium from viral attack. Hence, spacers serve as a ‘genetic memory’ of previous infections. These spacers are derived from DNA of viruses that have previously attacked the host bacterium. Interspersed between the short DNA repeats of bacterial CRISPRs are similarly short variable sequences called spacers (FIGURE 1). Figure adapted from Molecular Cell 54, Ap.
The molecular machinery cuts up and destroys the invading viral genome. The CRISPR RNA associates with and guides bacterial molecular machinery to a matching target sequence in the invading virus. The CRISPR sequence is transcribed and processed to generate short CRISPR RNA molecules. When a previously unseen virus infects a bacterium, a new spacer derived from the virus is incorporated amongst existing spacers. These regions are composed of short DNA repeats (black diamonds) and spacers (colored boxes). CRISPRs are regions in the bacterial genome that help defend against invading viruses. How does it work?įigure 1 ~ The steps of CRISPR-mediated immunity. Thus, by destroying the viral genome, the CRISPR immune system protects bacteria from ongoing viral infection. The genome of the virus includes genetic material that is necessary for the virus to continue replicating. If a viral infection threatens a bacterial cell, the CRISPR immune system can thwart the attack by destroying the genome of the invading virus. Just like us, bacterial cells can be invaded by viruses, which are small, infectious agents. The immune system is responsible for protecting an organism’s health and well-being. While seemingly innocuous, CRISPR sequences are a crucial component of the immune systems of these simple life forms. This name refers to the unique organization of short, partially palindromic repeated DNA sequences found in the genomes of bacteria and other microorganisms. What is CRISPRĬRISPR is an acronym for Clustered Regularly Interspaced Short Palindromic Repeat. This technology is referred to as “CRISPR,” and it has changed not only the way basic research is conducted, but also the way we can now think about treating diseases. Compared to previous techniques for modifying DNA, this new approach is much faster and easier. Within only a few years, research labs worldwide have adopted a new technology that facilitates making specific changes in the DNA of humans, other animals, and plants. Have you heard? A revolution has seized the scientific community.
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