The CRISPR Apostle: Rodolphe Barrangou • iBiology

Duration: 00:11:39
Transcript

00:00:43:07 - My lab would say Rodolphe, your car is on Twitter.
00:00:45:05 I'm like what are you talking about
00:00:46:19 my cars on Twitter?
00:00:48:18 Like before 2013 nobody would know what CRISPR is.
00:00:51:05 Now everybody knew what CRISPR was.
00:00:54:18 As a firsthand witness an apostle the gospel of CRISPR
00:00:58:21 it's beautiful complex compelling unbelievable.
00:01:03:10 (orchestral music)
00:01:12:00 (gentle music)
00:01:22:08 I've always been fascinated with the science
00:01:24:12 that goes into food.
00:01:26:11 Food is fun you know I mean who doesn't like food?
00:01:31:17 Things like cocoa get fermented to make chocolate.
00:01:37:03 Things like cabbage get fermented to make kimchi.
00:01:40:12 And my personal favorite is the bacteria that ferments milk
00:01:44:23 into tasty dairy products like yogurt and cheese.
00:01:53:09 It's fascinating. It's exciting.
00:01:55:09 You can let something grow for a couple of hours
00:01:58:05 and see liquid milk turn into this solid matrix
00:02:01:11 that you can scoop out.
00:02:02:21 There's things happening you know
00:02:05:01 before your eyes at human scale.
00:02:10:09 Back in the day I was working with a company
00:02:13:06 called Danisco.
00:02:14:18 It's a Danish food ingredient company
00:02:18:02 that doesn't have a history of publishing
00:02:21:01 a lot of scientific literature doesn't really care
00:02:23:13 about scientific dissemination of knowledge
00:02:25:22 but it's the world leader in manufacturing
00:02:29:05 and formulating cultures to ferment dairy products
00:02:33:07 into things like cheese and yogurt.
00:02:36:03 (orchestral music)
00:02:40:19 There are many challenges to making good yogurt
00:02:43:07 and good cheese.
00:02:46:21 One of the inconveniences of industrial operation
00:02:50:13 is that milk is not sterile when it comes to bacteria.
00:02:57:20 It's also not sterile when it comes to viruses.
00:03:01:03 Viruses of bacteria are called bacteriophage.
00:03:05:12 If you used to be French like I used to be French
00:03:07:10 you have to say bacteriophage.
00:03:10:15 When you get a strain that makes great cheese
00:03:14:01 great yogurt that gets slaughtered by a virus
00:03:17:11 you have to do what's called retiring the strain.
00:03:20:07 This strain may make the best yogurt in the world
00:03:22:19 but it gets slaughtered all the time.
00:03:24:09 Industrially you can't sell it.
00:03:26:04 So a key area of focus for dairy cultures company
00:03:31:16 like Danisco is to develop great cultures
00:03:36:10 that are resistant to bacteriophage.
00:03:39:06 So what scientists do is take a host
00:03:42:19 the bacterium is a host expose it to the virus.
00:03:47:03 The virus comes in and kills the large majority
00:03:52:00 but there's a small subset of the population
00:03:54:15 of bacteria that will make it.
00:03:57:17 We don't know why they make it but they make it a variant.
00:04:02:13 That's the survivor that withstood the attack
00:04:05:02 of the phage coming in.
00:04:09:06 We went back to the freezers from the nineties
00:04:12:05 back all the way to the eighties
00:04:14:06 and we sequenced some of those strains.
00:04:17:00 And when we compare the genome sequence of that variant
00:04:21:04 to that of the parent they look almost the exact same
00:04:26:10 across the whole length of those 2 million DNA letters
00:04:31:08 they look 99.9999% identical.
00:04:35:15 But there's a difference right at the CRISPR array.
00:04:42:03 The CRISPR array is a sequential combination
00:04:46:16 of a CRISPR repeats a spacer a CRISPR repeats a spacer.
00:04:52:06 In between those repeats those spacer sequences
00:04:55:13 are each unique.
00:04:56:22 (upbeat orchestral music)
00:04:59:20 So we have two strains repeat spacer repeat spacer
00:05:04:10 repeat spacer repeat all the same.
00:05:07:02 And at the very end at one of the extremities
00:05:10:20 there's one more repeat and one more spacer.
00:05:14:17 Like aha moment.
00:05:17:08 And that prompted us to do a series of three experiments.
00:05:25:11 We take a strain that same wild type strain
00:05:28:05 that is get slaughtered by that phage
00:05:30:13 and we expose that strain to the same phage.
00:05:33:01 What happens?
00:05:34:20 We let most of the bacteria die slaughter
00:05:38:19 and we look at the CRISPR content of the ones that make it.
00:05:42:18 We see repeatedly that when the strain becomes resistant
00:05:48:01 it has acquired a new spacer.
00:05:51:04 And that spacer sequence the small piece
00:05:53:05 of DNA that gets added on is a perfect match
00:05:56:10 to the phage that was used to do it.
00:06:00:10 And then what we do is we go back
00:06:01:18 to the host and we do the same thing
00:06:05:02 with a different phage and we see the same thing.
00:06:09:03 And in a kind of a cool twisted experiment
00:06:11:17 what we do is we give it a cocktail.
00:06:13:22 You blend different kinds of phages together
00:06:17:20 and we want to see what the host is gonna do.
00:06:21:05 And the host picks up a piece
00:06:23:13 of DNA from each one of those phages.
00:06:28:04 This suggests that there may be a correlation
00:06:32:17 between the CRISPR spacer content
00:06:35:18 and the ability of the host to become resistant.
00:06:38:17 So we're pretty psyched.
00:06:40:15 It looks pretty convincing.
00:06:42:07 It's still circumstantial evidence.
00:06:44:21 (orchestral music)
00:06:47:20 So you wanna show convincingly that
00:06:50:05 the CRISPR spacer content determines not correlates with
00:06:56:06 but determines sensitivity or resistance to a virus.
00:07:00:09 So the first thing we do is we add one.
00:07:04:01 And when you add a spacer synthetically
00:07:06:11 you become resistant.
00:07:09:16 Then we do the opposite.
00:07:12:02 So we go in and we take it away.
00:07:14:14 And when you remove the spacer that gives the resistance
00:07:17:16 you lose the resistance.
00:07:20:14 So that's pretty convincing evidence.
00:07:24:02 (orchestral music)
00:07:27:14 So we knew at the time the CRISPR locus
00:07:29:23 is accompanied by adjacent sequences
00:07:34:15 CRISPR-associated sequences called CAS genes.
00:07:40:12 So the question is if we tinker with those CAS genes
00:07:45:13 does it have an impact on the function of CRISPR
00:07:50:12 in providing resistance against the virus?
00:07:52:18 Next to this CRISPR array there's four genes
00:07:56:10 and in the first gene eventually will become known
00:07:59:05 as the infamous CAS 9.
00:08:02:05 We show that when you inactivate CAS 9
00:08:05:19 genetically you lose the ability to be resistant
00:08:10:17 to the virus though the CRISPR spacer is there.
00:08:15:04 The spacer just being there is not enough.
00:08:18:15 This implicates CAS 9 in immunity.
00:08:23:23 We now know that you need to have the spacer
00:08:26:21 but you also need to have CAS 9
00:08:29:12 for the spacer to be valuable.
00:08:32:03 And the second gene we knock out CSN 2
00:08:35:02 we don't impact resistance.
00:08:37:11 When you inactivate CSN 2 you lose the ability
00:08:41:11 to acquire new spacers.
00:08:45:03 We show that the CAS proteins are necessary
00:08:48:05 for both immunity to be expressed but also for immunization
00:08:53:23 to occur.
00:08:55:01 By tinkering with this one element
00:08:57:15 we've broken the CRISPR.
00:09:00:22 I'm so excited. I can't believe it.
00:09:02:08 Like that's that. That's cool like that's cool.
00:09:05:00 (upbeat orchestral music)
00:09:09:18 We were the first to show
00:09:11:14 CRISPR is the adaptive immune system in bacteria.
00:09:16:08 (upbeat orchestral music)
00:09:22:22 We publish our paper in March 2007 the first CRISPR paper
00:09:27:22 in high profile journal.
00:09:32:07 At the time our paper came out we are a bunch of nobody's
00:09:37:00 working at this Danish food ingredient company.
00:09:42:23 Authors who's never published anything worthy of a journal
00:09:47:19 like this talking about a topic that nobody cares about.
00:09:53:20 And now people care.
00:09:55:20 (upbeat orchestral music)
00:10:00:10 CRISPR has garnered the interest
00:10:04:10 of the whole world beyond scientists.
00:10:07:21 (upbeat orchestral music)
00:10:11:19 Oftentimes science is like building a mountain.
00:10:16:07 You start with you know the foundation
00:10:18:23 and then you build it one layer at a time.
00:10:21:01 And maybe the person sitting at the very top
00:10:23:05 of the mountain isn't the one that laid the foundation.
00:10:26:12 (upbeat orchestral music)
00:10:29:19 I'm one of the three or four people
00:10:31:13 who've been there since the beginning.
00:10:34:19 (upbeat orchestral music)
00:10:42:11 Keep calm CRISPR on and do your own thing.

This Talk

Speaker: Rodolphe Barrangou

Audience:

General Public
Educators of H. School / Intro Undergrad
Student
Educators of Adv. Undergrad / Grad
Researcher
Educators

Recorded: July 2017

Talk Overview

For millennia, humans have been harnessing microbes to produce everything from breads, to cheeses, to alcohol. Now these tiny organisms have produced another powerful revolution — the gene editing tool CRISPR. Rodolphe Barrangou, Ph.D., was working at the food company Danisco, where he was trying to produce yogurt lines resistant to contamination. In a series of groundbreaking experiments, he helped uncover what CRISPR was, how it worked, and why it could be so transformative.

Please head to the Science Communication Lab’s website for more films like this along with educator resources, full video transcript, and most up to date content.

View Educator Resources & Transcript on SCL Website →

More CRISPR & Genetics Films →

Speaker Bio

Rodolphe Barrangou

Rodolphe Barrangou

Rodolphe Barrangou studies beneficial microbes, focusing on the occurrence and diversity of lactic acid bacteria in fermented foods and as probiotics. Using functional genomics, he has focused on uncovering the genetic basis for health-promoting traits, including the ability to uptake and catabolize non-digestible carbohydrates. He spent 9 years at Danisco-DuPont, characterizing probiotics and starter cultures,… Continue Reading

Credits

Producers: Sarah Goodwin, Rebecca Ellsworth
Cinematographer: Derek Reich
Editor: Rebecca Ellsworth
Graphics: Chris George, Maggie Hubbard
Assistant Camera: Gray McClamrock
Drone aerials: Travis Jack
Supervising Editor: Regina Sobel
Field Producer: Meredith DeSalazar
Interview by: Adam Bolt
Associate Producer: Shelley Elizabeth Carter
Executive Producers: Shannon Behrman, Sarah Goodwin, Elliot Kirschner

Leave a Reply Cancel reply