5u31

Structural highlights

Function

CS12B_ALIAG CRISPR (clustered regularly interspaced short palindromic repeat), is an adaptive immune system that provides protection against mobile genetic elements (viruses, transposable elements and conjugative plasmids). CRISPR clusters contain sequences complementary to antecedent mobile elements and target invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA). In type II CRISPR systems correct processing of pre-crRNA requires a trans-encoded small RNA (tracrRNA), endogenous ribonuclease 3 (rnc) and this protein (By similarity). The tracrRNA serves as a guide for ribonuclease 3-aided processing of pre-crRNA (By similarity). Protein-crRNA-tracrRNA endonucleolytically cleave dsDNA target complementary to the spacer; protein is inactive in the absence of crRNA homologous to the target and tracrRNA (PubMed:26593719). Recognizes a short motif in the CRISPR repeat sequences (the 5' PAM or protospacer adjacent motif, TTN in this organism) to help distinguish self versus nonself, as targets within the bacterial CRISPR locus do not have PAMs (PubMed:26593719). PAM recognition is also required for catalytic activity. Cleavage results in staggered 6-8 base 5'-overhangs 14-17 and 23-24 bases downstream of the PAM (protospacer adjacent motif) on the non-target and target strands respectively (PubMed:27984729, PubMed:27989439). Both target and non-target strand DNA are probably independently cleaved in the same active site (PubMed:27984729).[UniProtKB:A0Q5Y3]^{[1] [2] [3]}

See Also

• Endonuclease 3D structures

References

1. ↑ Shmakov S, Abudayyeh OO, Makarova KS, Wolf YI, Gootenberg JS, Semenova E, Minakhin L, Joung J, Konermann S, Severinov K, Zhang F, Koonin EV. Discovery and Functional Characterization of Diverse Class 2 CRISPR-Cas Systems. Mol Cell. 2015 Nov 5;60(3):385-97. doi: 10.1016/j.molcel.2015.10.008. Epub 2015, Oct 22. PMID:26593719 doi:http://dx.doi.org/10.1016/j.molcel.2015.10.008
2. ↑ Yang H, Gao P, Rajashankar KR, Patel DJ. PAM-Dependent Target DNA Recognition and Cleavage by C2c1 CRISPR-Cas Endonuclease. Cell. 2016 Dec 15;167(7):1814-1828.e12. doi: 10.1016/j.cell.2016.11.053. PMID:27984729 doi:http://dx.doi.org/10.1016/j.cell.2016.11.053
3. ↑ Liu L, Chen P, Wang M, Li X, Wang J, Yin M, Wang Y. C2c1-sgRNA Complex Structure Reveals RNA-Guided DNA Cleavage Mechanism. Mol Cell. 2017 Jan 19;65(2):310-322. doi: 10.1016/j.molcel.2016.11.040. Epub 2016, Dec 15. PMID:27989439 doi:http://dx.doi.org/10.1016/j.molcel.2016.11.040