Advances in CRISPR/Cas9

Figure 1

CRISPR/Cas9-mediated bacterial adaptive immunity. A typical type II CRISPR/Cas locus consists of a set of Cas genes (colored ellipses), a series of repeats (yellow diamonds) and spacers (green rectangles). When phages infect a cell, the cell will capture and integrate the phages’ DNA fragments into the CRISPR array. Spacers are then transcribed into crRNA precursor (pre-crRNA) (brown line) and paired with tracrRNA (blue line) to be cleaved into mature crRNA by RNase III. crRNA recognizes foreign DNA through complementary pairing and guides Cas9 to make site-specific DNA breaks on foreign DNA [20].