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Imagine
You install um like a state of our security system in your house
Right something really high end exactly
But this isn't
You know your standard motion detector imagine a system that doesn't just sense of burgler
But if physically rescopiititself to rarap the exexact um the exact molecular itself of the the ggl's specific crow bar
Which is a crazy visual
It is
And then it reaches over grab your own television remote
And uses that to trigger a housewide alarm
I mean it sends like complete science fiction
Oh
Absolutely
But today on our deep dive
And we're looking at research proving this is exactly how acaciia fight off viruses at a microscopic level
It aa massistacack data remode from you know complex genetic screens to a high resolution structural imaging theis a so much to unpackyer
There really is an our mission
Today is desect ct mechanics of this ancient shifting immune system
Until every single piece of this ancient battlefield makes perfect sensentive
It's um
It really is a remarkable piece of research
Primarily because it just ships our entire perspective on community
Ity know well for a long time
We viewed structure based pattern recognition
So the abability of imimunune system
The phyamically detect a specific pathogship
We
We view that as a highly evolved for it
Something you only see in complex organisms like in human beings
Exactly
But the data or looking at establishes this as a fundamental ancient strategy across all domains of life
The completely reframes or understanding of the evolutionary arms race between bacterial uh the viruses that hunt them
Which we call ages
So to really understand how this microscopic security system actually works
We need to lay down some foundation tional bithology for you
The paper focuses heavily on something called a pattern recognition receptor
It's specifically one the belongs to the um the stand ant pace superfamily so the stand proteins
Yeah
Let's break that down for someone who might not be looking at protein structures
Every single day yeyou exactly is this receptors
What makes this stand family so unique
Okay
So a pattern recognition recepter is essentially well
It's bibilogical sensor roaming the interior of a cell
Its entire purpose is to sccan the environment for molecules
That look foreign biologists call these pathogen associated molecular patterns
But it a comicicous dumble on precisely now stand is an acronym
It stands for signal transduction at paces with numerous domain
Which is a very heavy technical term
It is yeah
But it just describes a massive multipprotein
That
That ach
But both the detector and the executioner
You see most proteins just have a single job right but stand proteins are unique
Because they combine multiple functional tools into one continuous structure
It sounds like
Like a microscoppic triprotypes
Who is army knife
You have three main components folded into one unit
That's a really good way to think about it
Yeah from what i'm reading on one end the a ternal
You have the sensor
That's the magnifying glass looking for threats
Which is usually made of repeating structural loops
Things
They called tpr repeats
Awd forty beta propellers
Exactly
And then wrin the middle
You have the engine
The central nt pace domain
Right right that's a battery packpowering the home machine and finally in the other end
The interterminal
The the effect and the the teteand a many casloit's a nuclear desigch to just seed protein and inthe tieet seular deaths to start a virus in its tracks
Yeah
That three ararchitechture is exactly what the researchers looking for like finding them across the entirety of the bacterial world
I mean that require some intense bioinformatics
I can imagine to understand the sheer scale of the defense network
They deployed a highly sophisticated aloriorimic search
They started with six hundred and fifty six known seed protein
Seed protein so like stand proteins
We like the nuwer revolved in immunity exactly
And from there they used an algorithmmc tool called
Psi blast
You can think apsi blast as like a biological search engine that scwers you know make dabases for distant evolutionary relatives by comparing their ammino acid sequences
Okay
So they feeat in the six hundred and fifty six ceeds
And through this tool
They expanded that initial pool to almost three hundred and sixty thousand diverse protein sequences
Across five hundred and eighty nine distinct evolutionary branches or clades three hundred and sixty thousand sequences is a stagering amount of genetic data
嗯
But i mean just because a protein has that three part structure doesn't necessarily mean fununctions as an immune system
Right that is exactly the problem they face
So how do you filter a data set that massive to find the ones
That actually fighting on viruses
You have to apply rigorous evidence datthe researarers use two distinct criteria to filter out all that noise
First they looked at the genetic neighborhood
Using a computational tool called defence fider der right bacteria group through defence genes together
Right right acacteria are incredibly efficient with their dna
They tend to group defence genes closely together on their genome sort of like a militarized zone
So defence finder ter cuculates a statistical probability to see
If these newly discovered stand genes consistently appear right next to other known established defence systems that makes perfect sense
And the second critersecond they looked at the structure
Itself they screen those sequences for the presenof known weapondomains like the nuclelsses evitioned data
The combining that genetic neighorhood data with the structural data
They narrowed it down to hundred ninety eight confident defense associated claids
While looking through the filogenetic trees
They built from that data a specific human gene jumped out of me
Um opaff one uh yes a puff one for anyone familiar with human solular biology
Um opaff one is the core ore onent of the apopsm
Um
It's the solular machinery
That causes our own cells to undergo program sold that the poptoses when they are severely damaged or mutative
Which is an essential function in our body of the exactly
But the data here suggest acterial have the exact same machinery
The evolutionary link is profound
The researchers identified bacterial ththologs of a path wine primarily in ciano acterteria
These bacterial teins share structurally identical beta propeller sensors with human oppaf phone wow
But there is a functional difference
And how they execute command human oppaf one uses a recruitment omomin to call in other downstream proteins to initiate cell death
It's a cascade
But the acaciiversion they have a cast space like proteace built directly into their end terminal
The weapon is permanently attached
It is a much more direct ancient mechanism for sayler suicide okay stepping back for second
Let me just make sure
I have this whole picture maps down few guys listening
So they do a quickly gap bullet one we started by looking at stand proteins
Which are these versual three part immune sensors with a detector in engine and a weapon bulletu by using this massive genetic search engine
The researchers prove these sensors aren't rare
Anomyalies
There are hundreds of thousands of them organized into nearly two hundred distinct defence families and both three these bacterial systems share deep evolutionary routes with the very machinery
Our own human bodies used to clear out damage cells
It's an unbroken lineuage of self defence stretching back billions of years
It really makes you wonder
有i want you
You think think about your imimmune system
Right now if acacteria have been refining these cellar self destruct mechanisms for that long what other fundamental parts of our own biology
Which just upgraded versions of something a single cell organism invented to fight a virus
That is a great question and the complexity they'developed over those billions of years is exactly tly what study dy highlights next they
They mapped out the massive global twororof defence systems
The researchers needed to see how one actually functions in real time right zooming in exactly
So they isolated a completely uncharacterized family of these stand proteins
Which they named as seven
And when they looked at have seven
They found that it along with another entirely unrelated defence system called dsr
One was targeting something called the mcp right
So the picture this microscopic battle of you
We need to know what the mcp is in
Why a acacterial censor would be looking for it
Well
Mcp stds for majacic protein
When a fage infects of acacteria
Its ultimate goal is to replicated dna and build new viral shells
To in case that dna the shell is the capid and the m cp is the primary building block
Okay
So it's looking for the viral building material exactly entailed ages use a highly conservve
Highly stable three dimensiononscshape for the building block known as the hk ninety seven fold and a fold just refers to the specific complex way the protein chae twists and folds in on itself right
And the researchers discovered the f seven
It is esspecialized bilob sensor domain
Who sold purposing life is to detect the specific curvure ure of that henninety seven fold
But identifying a target computation is one thing
How do you actually prove that the mcp is the specific trigger in a lab
I mean the virus is incredibly complex and produces dozens of different proteins during an infection
That is where they utized uh highly elegant genetic screen
It is essentially a survival of the fitdest essay on a molecular level
I love how did did this part
Yeah
It's brilliant
They took library of specifiand eighty seven different individual al es from a specific fiages wn as the only eighteen
They attached a unique dna barx al to every single one of those genes
Then they introduce this entire library of barcocoded viral genes into a population of ecoa acterteria
That had been engineered to express the f seven security system
So you basically have this massive pool of bacterial each one is holding a different piece of the virus
Precisely
And because and seven seven triggeers selular suicide
Any acacteral cell that receives a viral
See that bactiortes the system will instantly die
Wow Yeah
And when the cell dies its specific barcoers disappears from the growing population
So by using next generation sequencing on the bacteria al survive
They could look at the data and see
Exactly which barcode was missing the results were eneniable the gene in coding the major caampular protein
When the unique activator
When the mcp was introduced the trap spring in the cells dive
It was the only trigger
But
But the data shows f seven doesn't catch the mcp alone
是的是的
This is the part
That myors grabbing the television remote to trigger the alarm as seven actually kidnappse a acterial protein called ef two or e longation factor two
Yes
The host factor to us right now hold on ef two is not some random expendable protein life
It is absolutely crucial for the bactery's normal life
Its job is deliver a meo assets to the riozone to build proteins
And because the acteriory is always building proteins
Ef two makes up roughly sixty ten percent of the entire cellular mass isn't
The bacterial sabotaging its own essential infrastructure by using it for defence
It definitely appears counterintuitive at first
But from an evolutionary perspective
It is a master class in energy conservation
The researchers performed binding essays and found that f seven specifically targets the inactive gdt bound form of ef two
It binds a precise one to one to one ratio with the fige mup and the as seven cense
How i see so intentially grabbthe bulocck of are on a break rather than disrupting the active ones
Yes exactly by coopting an incincdiacly a londhohost protein that is teororary rerebut the fs seven seven ffence stem avoids having to manufactureits own structural scuffolding that is so smart
It really is ef two acts a biyugical breace
It's incstrudiorally stabilizes the trap
Which is dramatically enhances eve seven sensitivity to the viral protein
The data shows that without ef two the as seven sensor is sluggish and inefficient
But with ef two acting is scaffolding
It forms the complex almost installing it buds that for our next recap so summarizing this phase of the discovery bullet one resumed in on eof seven
And found its target is the main building block of the viral shell
The mcp right bullet two scienproprove of the the massive genetic screen by putting six hundred and eighty seven barcocoded viral genes into ecoi i and bullet three have seven recruits the hosts own hosting ef to do to build its trap saving energy and boosting reaction time that combination creates a highly prime incredibly sensitive trickware
It's a brilliant engineering solution
Think about it
If you were designing a security system in a giant house
Would you build every part from scratch
Or would you borrow the infrastructure already in the walls
But would brbring up the most pressing question for me
对的对的
What happens the moment that trick widers crossed
How do these three ingredients have seven fm seven the viral mcp and the hijaked ef two physically move to visualize that mechanism the research team utilized crogenenic electron microscope y crio em
Which is an amazing piece attack
Absolutely this involves flash freezing the proteins and thin layers ers nnon crystan ice
Which preserves their natural shape and this mumbaring them with electrons to capture high resolution images through this
They were able to map out an active complex
That forms a one megadultin a ymmetrical ttrimor through one megadultton ttrimor meaning four distinct copies of these protein complex is snap together to form one massive mechanical structure
I like to think of it is the butterfly of doom
Because of its shape that is a very apt name for it
The researchers map this out as a highly specific four state process
Let's walky through the mechanics of it stepped by step state one is the apo or arresting state rate
Yes before virus arrives the have seven protein is sitting in the cell auto inhibited
It is essentially dorain the central engine
The ant payed domain is bound to a low energy molecule called adp
The crucial feature of this resting state is that the weapon the cap four
Four nucleous domain is physically tucked away away
It is suesttered and hidden
Which makes perfect sense
You don't want a robe nucleus floating around the cell threating the acacteria is own dna by accident
Exactly the weapon must be shieelded
That brings us to state to the clamp a fage infects the cell bebegsysympthesizing those mct building blocks
The f seven cenor or detex hkn ty ding blocks
But it doesn't just razed the sensor physically in gulks the viral protein varying three thousand seven hundred square anggterms of surface area
Let's just put that number of struspective and anexterum is the unit of measurement we use for atams
It is unimagerably small
So when the paper states of the two lobes of the sensor clampdown down
Cause used at thirty exterum structural shift to a listener
Thirty anexgterms might sound infanattessmall it does sound small
But on a molecular level
Where you were dealing with rigid atomic bonds
A thirty extra movement is an earthquake is massive physical lever being thrown
It is a violent structural rearrangement
And that thirty antrtral shift is the catslist for state three assembly
Because the censor has clamped down
So forcefully
It physically crashes into the resting engine domain
Wow Yeah
This structural clash forces hientipace engine to pre open the low energy atp is physically ejected
And a high energy atp molecule rushes into the pocket to bind the engine is now active
This physical domino effect leads directly to state for the final tetra reformation with the engine power by atp
It is a complete f seven units
Along with their trapped viral proteins in the borrowed ef two scavling they all snapped together
Forming that buterfly structure
It's exactly this assembly brings the four hidden camp four weapon omomaout out of hiding enforddattrtic in the center
They aligned to form an active inward facing nuclaasis ically becomes a molecular wdshiaper
It puls the viral d na into the center of this four part part cell
And just sure it
It destroying the cell before the virus has a chance to replicate the machanistic precision is profound three a similless cascale from a shape recognition event to a thirty anexim physical shift to a nuclear tide exchange resulting finally intetetermorizft every single step is a mechanical pell safe to ensure the weapon only fires when the cell is definitively under attack
Okay
Let's trace up physical pathway one more time to slitified recap three bullet one in state one the ads seven system is sleeping butching a low energy adp molecule with its weapon safely hidden right bullet two the viral protein enters and the sensor clamps down on it causing a massive thirty antreum physical shift
It shift causes a crash and state three ejecting the adp and powering ing engengine bulp three bullet three
Three that power allows weapits to snap together in state four exposing your weapons
And forming a rather that destroys the viviral dna
The fact that this is a purely mechanical physical reaction
Happening millions of times inside a single cell is what makes molecular biology so fascinating
Can you picture that thirty extreme shift it's like a beare trap snapping shut on a molecular level
And it brings us to a massive realization ads seven is a marvel of biological engineering
But the researchers instop there
They asked the obvious next question
And they went just a one often ommily or is this happening everywhere right
So they went back to the genetic scening algorithm
But they dramatically scale that up
They took thirty more uncharacterized cenor clusters from from their initial dabase
And they asked them against a library of six hundred genes pulled from thirty six highly diverse pages
And they hit the jackpot
I mean they didn't just find one or two more they discovered thirteen brin new ads families
Which they categorized as s eight and ads ten three twenty one
What is truly revolutionary about these thirteen new families is the diversity of a viral hardware
They are monitoring
They are just looking for capcapshoors anymore
No
They're looking
Looking
Where
Where actly these new sensors
Tararporporal adapters
Tatanonoseles
Head
Tail connectors
Tate measure proteins
And even the viruses own replicictive machinery like dna polymoraces of hellecases or tail novel or portal adapters
I mean these are the structural pieces of virus uses to physically punctual a cell membrane uninjected dna
So the acterial are essentially monitoring every single crucial unchangeable piece of hardware of virus needs to functions
That's right and the way
They recognize these parties brilliant
The researchers used alphold three the ai tool that predicts three dimensional protein structures from amminoasid sequences to model how these new new ililies by into their targets
嗯
The model show that these sensors aren't just looking for a tiny chemical tag on the outside of the virus
They inveloed the entire conserved core fold of the target completely ignoring the variable mutating parts in the surface
The analogy of wrapping the engine blog works perfectly here
If you want to identify a specific cor
You could look at the paint color or the bumper
But those are easily change right you just swap amount exactly by targeting the core fold
If a tial al al evolueral protein the biological engine block the acteriia ensures the viruses trapped
If a virus attempts to mute its core fold to escape detection the structural integrity of the virus fails the protein just stops working
It's an ineescapable evolutionary chequin
So we walk through this entire microscopic wars on final recape
We've seen the sheer scale of the thirty new families
How they target almost every essential viral component from tail momozles to plum races
And how they achieve this by engulfing the unchangeable core fold of the virus
So accan't mumuate the escape
But what does this all mean for you listing
Why is understanding the precise mechanism of bacterial immune system relevant to the average person
Well because understanding this blueprint provides us with a profound therappeuuc horizon
We are currently facing a global crisis of antibiotic resistant superbugs
If bacterial this efficient at identifying essential viral parts and triggering selular lar suicide
We can harness that mechanics
That is so exciting it is on one hand we could sigsigoff the sheleltherapeotic pages engineinered specifically to evade these bacterial censors allowing us to treat acacteria infections that no longer respond to traditional ananbiootics
On the other hand
We could look at the triggers themselves the specific viral shapes that caused that thirty extrum shift and design new antii microbial drugs that artificially mimic those shapes
Oh wow
So we could trick a deadly antibiotic resistant superbug into triggering its own abs suicide bathway
Exactly we use their own security ity system against them
It is a perfect example of how diving into the fundamental highly technical mechanics of single protein can open up entirely new frontiers in modern medicine
Well
Thank you for taking this deep dive with us
Today we've gone from the broad algorithms of evolutionary biology down to a thirty ank's from structural shift and explore how a microscopic security system reshaves itself to protect a cll
But
But we wrapped up i want to leave you with one final thought to mull over it's really interesting point
Yeah
We've just explored how brilanant have brliania have evolved to trigger ourself to struct sequence the absolute second day sense of viral tail tube or core caps proprotein
It's an in the escapable trap
But in biology there is always a countermove
Could a virus eeventually evolved to exploit this exact system
Could virus learn to produce decoy core proteins
Imagine a virus arriving in a bacterial cell and simply flooding the environment with fake puzle pieces triggering the bacteria to destroy itself before the real virus even attempt to enter the cell
It's a multi billion year old evolutionary arms race and the rules are always changing
Keep question and keep exploring
And will catch you on the next deep dive
