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Part:BBa_K1773005
I-F type CRISPR-Cas Cascade complex
I-F type CRISPR-Cas Cascade complex, which has a mutated EcoRI restriction site to make it biobrick compatible. This protein complex needs to be coexpressed with a crRNA region, to make a functional Cascade ribonucleoprotein complex. Together With Cas3 (BBa_K1773003) degrades DNA.
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25INCOMPATIBLE WITH RFC[25]Illegal NgoMIV site found at 1790
- 1000INCOMPATIBLE WITH RFC[1000]Illegal BsaI.rc site found at 2307
Usage and Biology
Cascade (CRISPR Associated Complex for Antiviral Defence) complex is an essential component of I-type CRISPR-Cas systems. This ribonucleoprotein complex is coded by 4 genes in an operon : Csy1, Csy2, Csy3 and Cas6f, with stoichiometry of 1:1:6:1 respectively. Also it has a crRNA molecule, witch acts like a guide, that brings the whole complex to the target dsDNA sequence. Each Cascade complex has a unique Protospacer adjacent motive (PAM) recognition site. The recognisable PAM sequence of this specific I-F Cascade complex from Aggregatibacter actinomycetemcomitans recognises CC nucleotides directly upstream of the protospacer (the target sequence). In other words, a target sequence needs to have a CC pair on the non-complementary strand of DNA -2 -1 positions of the protospacer. When Cascade complex finds and recognises the DNA target, then Cas3 (BBa_K1773003) is recruited for DNA degradation.
The wild type Cascade complex had EcoRI restriction site inside the coding region of Csy1 gene.
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