CRISPR acts as commander-in-chief for backup defenses in bacteria
The main function of CRISPR-Cas systems is to defend bacteria against various threats, including viruses called bacteriophages. Researchers have continued to study all varieties of CRISPR-Cas systems (to date, two classes, seven types and 46 subtypes have been identified) to understand their capabilities.
This study, led by Dr. Yan Zhang of the University of Michigan Medical School, reveals a previously unrecognized feature of the type I CRISPR-Cas system in Neisseria bacteria. The research found that type I CRISPR-Cas systems moonlight as a manager, regulating the expression of built-in defense systems against phages. Typically, production of these defense genes is held in check to prevent costs to bacterial growth.
However, when CRISPR-Cas is defective or disarmed, repression is lifted, leading to a burst of production of innate defense systems as backup weapons. This layered regulatory hierarchy acts as a commander-in-chief, coordinating the repression and derepression of defense genes within the CRISPR-Cas locus. The discovery could have implications for industrial applications, such as engineering phage-resistant bacterial strains for yogurt and biofuel production.
It also could aid in the development of more effective phage therapies for antibiotic-resistant bacterial pathogens.
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