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4 weeks ago
Farhat
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0
I'm learning about CRISPR at my college.
I understand that when viral DNA is inserted into a bacterial cell, the Cas1-Cas2 proteins identify the PAM site in the viral DNA and then cut the protospacer from the viral DNA to make it a spacer in the CRISPR array for the adaptive immunity of the bacteria. I'm confused about why they need the CRISPR system if the Cas1-Cas2 cuts the protospacer, and at that time only the viral DNA gets inactivated.
Then what is the need for Cas9 in bacteria?
It infers adaptive immunity for the bacterium against invading foreign DNA, think phage/viruses.
But cas1-cas2 is also doing the same thing right?
Those are different types of nucleases. They form part of the CRISPR system. See: https://en.wikipedia.org/wiki/Cas12a
Thanks. Now I understood it