| Description: | CRISPR-Cas9, a revolutionary molecular tool, constitutes an adaptive immune system that defends against mobile genetic elements like viruses, transposable elements, and conjugative plasmids. In this system, CRISPR clusters contain spacers, which are sequences complementary to preceding mobile elements, serving as a memory bank of past encounters. The process involves transcription and processing of CRISPR RNA (crRNA), wherein, for type II CRISPR systems, the proper processing of pre-crRNA requires a trans-encoded small RNA (tracrRNA), endogenous ribonuclease 3 (rnc), and the pivotal Cas9 protein. The tracrRNA guides ribonuclease 3 in processing pre-crRNA, with Cas9 stabilizing the pre-crRNA:tracrRNA interaction. In subsequent steps, Cas9/crRNA/tracrRNA complex acts as an endonuclease, cleaving the target DNA with complementary spacer sequences. Cas9 is inactive without the guidance of two specific guide RNAs (gRNA), emphasizing the necessity of both gRNAs for DNA binding and nuclease activity. Cas9's recognition of the protospacer adjacent motif (PAM) within CRISPR repeats is crucial for distinguishing self from nonself, ensuring accurate target identification. This sophisticated system confers immunity against invading genetic elements through a mechanism known as CRISPR interference. CRISPR-Cas9 Protein, S. pyogenes (His) is the recombinant CRISPR-Cas9 protein, expressed by E. coli , with tag free. The total length of CRISPR-Cas9 Protein, S. pyogenes (His) is 1367 a.a., with molecular weight of ~163 kDa. |
