WEBVTT NOTE This file was generated by Descript 00:00:01.740 --> 00:00:06.060 The CRISPR Cas9 system is a tool for cutting DNA at a 00:00:06.060 --> 00:00:07.950 specifically targeted location. 00:00:10.290 --> 00:00:14.580 The technique has already revolutionized gene editing, but scientists are 00:00:14.580 --> 00:00:16.290 always looking for new possibilities. 00:00:16.890 --> 00:00:18.930 So what else can CRISPR do? 00:00:25.905 --> 00:00:29.295 Since being discovered in a bacterial immune system, CRISPR 00:00:29.295 --> 00:00:33.045 Cass nine has been adapted into a powerful tool for genomic research. 00:00:34.065 --> 00:00:35.745 There are two components to the system. 00:00:36.405 --> 00:00:41.595 A DNA cutting protein called Cas9 and an RNA molecule 00:00:41.775 --> 00:00:44.955 known as the guide, RNA Bound. 00:00:44.955 --> 00:00:50.295 Together they form a complex that can identify and cut specific sections of DNA 00:00:52.545 --> 00:00:55.965 first Cas9 has to locate and bind to a common sequence 00:00:55.965 --> 00:00:57.405 in the genome called a Pam. 00:00:59.205 --> 00:01:03.555 Once the PAM is bound the guide, RNA unwinds part of the double helix. 00:01:05.415 --> 00:01:10.155 The RNA strand is designed to match and bind a particular sequence in the DNA. 00:01:12.015 --> 00:01:15.615 Once it's found the correct sequence, Cas9 can cut the DNA. 00:01:16.185 --> 00:01:20.415 Its two nuclease domains each make a nick leading to a double strand break. 00:01:22.545 --> 00:01:26.565 Although the cell will try to repair this break, the fixing process is error 00:01:26.565 --> 00:01:31.245 prone and often inadvertently introduces mutations that disable the gene. 00:01:32.955 --> 00:01:36.615 This makes CRISPR a great tool for knocking out specific genes, 00:01:40.125 --> 00:01:43.155 but making double strand breaks isn't all CRISPR can do. 00:01:44.025 --> 00:01:47.715 Some researchers are deactivating one or both of Cas9's cutting 00:01:47.715 --> 00:01:49.755 domains and fusing new enzymes onto. 00:01:49.785 --> 00:01:54.435 A protein Cas9 can then be used to transport those enzymes 00:01:54.494 --> 00:01:56.595 to a specific DNA sequence. 00:01:58.245 --> 00:02:01.995 In one example, Cas9 is fused to an enzyme, a deaminase, which 00:02:01.995 --> 00:02:04.215 mutates specific DNA basis, 00:02:06.554 --> 00:02:11.505 eventually replacing cytidine with thymidine, this kind of precise gene 00:02:11.505 --> 00:02:15.015 editing means you could turn a disease causing mutation into a healthy 00:02:15.015 --> 00:02:19.005 version of the gene, or introduce a stop code on it, a specific place. 00:02:20.565 --> 00:02:22.635 But it's not all about gene editing. 00:02:23.204 --> 00:02:27.585 Several labs have been working on ways to use CRISPR to promote gene transcription. 00:02:28.935 --> 00:02:32.385 They do this by deactivating Cas9 completely, so it can 00:02:32.385 --> 00:02:34.845 no longer cut DNA Instead. 00:02:35.025 --> 00:02:39.045 Transcriptional activators are added to the Cas9 by either fusing them 00:02:39.045 --> 00:02:42.615 directly or via a string of peptides. 00:02:45.345 --> 00:02:48.465 Alternatively, the activators can be recruited to the guide RNA. 00:02:48.465 --> 00:02:52.935 Instead, these activators recruit the cells transcription machinery, 00:02:54.075 --> 00:02:58.365 bringing RNA polymerase and other factors to the target, and increasing 00:02:58.365 --> 00:02:59.655 transcription of that gene. 00:03:01.995 --> 00:03:08.115 The same principle applies to gene silencing a crab domain fused to the Cas9. 00:03:08.310 --> 00:03:12.780 Inactivates transcription by recruiting more factors that 00:03:12.780 --> 00:03:14.130 physically block the gene. 00:03:17.730 --> 00:03:21.360 A more outside the box idea for using CRISPR is to attach fluorescent 00:03:21.360 --> 00:03:25.140 proteins to the complex so you can see where particular DNA 00:03:25.140 --> 00:03:26.970 sequences are found in the cell. 00:03:28.050 --> 00:03:30.270 This could be useful for things like visualizing the 00:03:30.270 --> 00:03:32.160 3D architecture of the genome. 00:03:33.960 --> 00:03:37.950 Or to paint an entire chromosome and follow its position in the nucleus. 00:03:39.990 --> 00:03:44.460 CRISPR has already changed the face of research, but these new ideas show 00:03:44.550 --> 00:03:46.140 that what's been achieved so far. 00:03:46.185 --> 00:03:49.935 Could just be the tip of the iceberg when it comes to CRISPR's potential, 00:03:52.365 --> 00:03:53.445 whatever comes next. 00:03:53.535 --> 00:03:56.655 It seems the CRISPR revolution is far from over.