the crisper cast 9 system is a tool for cutting DNA at a specifically targeted location the technique has already revolutionized gene editing but scientists are always looking for new possibilities so what else can CRISPR do since being discovered in a bacterial immune system CRISPR Castine has been adapted into a powerful tool for genomic research there are two components to the system a DNA cutting protein called Cass 9 and an RNA molecule known as the guide RNA bound together they form a comp
lex that can identify and cut specific sections of DNA first cass 9 has to locate and bind to a common sequence in the genome called a perm once the pam is bound the guide RNA unwinds part of the double helix the RNA strand is designed to match and bind a particular sequence in the DNA once it's found the correct sequence Castine can cut the DNA it's to nuclear's domains each make a neck leading to a double strand break although the cell will try to repair this break the fixing process is error-
prone and often inadvertently introduces mutations that disable the gene this makes CRISPR a great tool for knocking out specific genes but making double strand breaks is an all CRISPR can do some researchers are deactivating one or both of cass nines cutting domains and fusing new enzymes onto the protein cast line can then be used to transport those enzymes to a specific DNA sequence in one example cast nine is fused to an enzyme a deaminase which mutates specific DNA bases eventually replacin
g site adine with fiber dean this kind of precise gene editing means you could turn a disease-causing mutation into a healthy version of the gene or introduce a stop codon at a specific place but it's not all about gene editing several labs have been working on ways to use CRISPR to promote gene transcription they do this by deactivating cast line completely so it can no longer cut DNA instead transcriptional activators are added to the cast 9 by either fusing them directly or via a string of pe
ptides alternatively the activators can be recruited to the guide RNA instead these activators recruit the cell's transcription machinery bringing RNA polymerase and other factors to the target and increasing transcription of that gene the same principle applies to gene silencing a crab domain fused to the casts 9in activates transcription by recruiting more factors that physically block the gene a more outside-the-box idea for using CRISPR is to attach fluorescent proteins to the complex so you
can see where particular DNA sequences are found in the cell this could be useful for things like visualizing the 3d architecture of the genome or to paint an entire chromosome and follow its position in the nucleus CRISPR has already changed the face of research but these new ideas show that what's been achieved so far could just be the tip of the iceberg when it comes to crispers potential whatever comes next it seems the CRISPR revolution is far from over [Music] you [Music] [Music]
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