Question

3. (Chapter 17, C13 of text) What are the roles of Cas1, Cas2, and Cas9 proteins in bacterial genome defense?

Answer 1

The Cas1 is an universally conserved protein which is found in the CRISPR prokaryotic defense system. It is a metal dependent DNA specific endonuclease and is able to produce double stranded DNA fragments. It helps the bacteria to adapt to new viral infections. Cas2 is another conserved protein that works along with Cas1. Both the conserved proteins i.e Cas1 and Cas2 together form the integrase complex. Cas9 is an RNA guided DNA endonuclease enzyme which is associated with CRISPR and it helps in memorizing a foreign DNA and later cleave the same.