Deploying artificial genes to overcome antibiotic resistance | Logan Collins | TEDxMileHigh

Deploying artificial genes to overcome antibiotic resistance | Logan Collins | TEDxMileHigh


Translator: Kirstie Neo
Reviewer: Denise RQ Antibiotic resistance is an extremely serious threat
in today’s world. It cost the US healthcare system
over 20 billion dollars per year. And it kills an estimated 23,000 people
per year in the US alone. In addition, there are concerns that antibiotic resistance might result
in something far worse. It may result in something along the lines
of the bubonic plague, which killed approximately a third of Europe’s
population of the time that it occurred. We, of course, don’t want this. (Applause) So what’s being done about this? Well, traditional antibiotics
tend to use compounds which will fit into
the molecular machines that run bacteria. the macromolecules, those large molecules,
that help to make bacteria work. And what they do
is they’ll fit into a particular crevice as a key fits in to a lock. And the antibiotics will inactivate
these macromolecules and disrupt their function,
thus killing off the bacteria. However, when bacteria in the population
have variations of these molecules, which are differently shaped, the antibiotic key can no longer fit
into the large molecular lock. And thus, the bacteria gains resistance. Then these bacteria
propagate in population, and it results in an antibiotic resistance
population of bacteria. There are also some other ways
that antibiotic resistance arises, including antibiotics
not being able to enter the cell, antibiotics being pumped out of the cell, and enzymes which will chop up
the antibiotics. I’ve been conducting research
at the University of Colorado, Boulder, at the Chatterjee Lab, and thus far,
I’ve gotten some very encouraging results, and I’m excitedly continuing
to pursue the next steps in my research. So what have I been doing? I have created an artificial gene
that codes for antimicrobial polypeptides. This artificial gene is… Well, let me first explain
what that means. (Laughter) (Applause) Basically, I created a gene
that is capable of synthesizing misfolded proteins upon entering
into the bacterial cell. These misfolded proteins disrupt the biochemical balance
in the bacterial cell by causing chaos through aggregation. And I’ll get back to that
in just a moment. As you can see, this causes
a widespread disruption in the bacteria, rather than targeting a specific molecule. And because of this,
it’s got great promise in being more effective
than traditional antibiotics because the bacteria won’t be able to
simply change the shape of one molecule. They will have to undergo
a system’s wide adaptation if they are to gain resistance. In designing this gene, I first wrote out
an amino acid sequence. And then I converted it
to a DNA sequence using software. In the design of this,
I included several key elements I included a promoter,
an open reading frame, and a terminator. And the promoter is simply
a piece of the DNA that is capable of activating the gene. That is, it’s what the bacteria
are able to turn on once the gene has entered their cell. And this could be made specific
to specific types of bacteria. The terminator turns off the gene
once it’s finished being transcribed. It limits it to just the specific sequence
that is to be translated eventually. And the open reading frame contains the actual information which will go into the sequence of the gene,
or the polypeptide, that is. When designing this gene, I specifically included
a lot of hydrophobic amino acids. And the reason for this was because I was trying
to vastly increase the likelihood that aggregates would form
in the bacterial cells. As I’ve mentioned earlier, aggregates can be toxic and cause chaos
through a variety of mechanisms. The reason that hydrophobic
polypeptides tend to aggregate is because they clump together
in the presence of water. They are afraid of water. It’s more thermodynamically favorable
for them to avoid water. So, by clumping together, they minimize the exposure of their surface
to the water in the bacterial cell. This also provides potential benefit in that the aggregates most likely
would be much more difficult to remove from the bacterial cell as traditional antibiotics are
when they are pumped out. Another benefit of having
very hydrophobic polypeptides is that they may take on multiple shapes. This is because the polypeptides wouldn’t necessarily just have
one way of folding because they’d always be exposing
hydrophobic patches. They’re so hydrophobic there’s no way for them to hide
all of the hydrophobic bits. And so, they would have to, depending on the environment in the cell, be re-folding themselves to maximize
the amount of the surface area that’s being hidden from the water. And because of this,
it would possibly be more difficult for bacteria to recognize
specific shapes of the polypeptides to chop up with enzymes. To deliver this, I’ve decided that bacterial conjugation
is an ideal delivery system, and I’ve begun to work on this. And as I’ve mentioned, I’ve gotten
some very promising results with it. So bacterial conjugation is the transfer
of DNA from one bacterium to another. It’s essentially bacterial sex. And because of this, it’s another potential barrier
to antibiotic resistance because bacteria have been using this
to their advantage for millions of years. And as a result, to remove their ability to conjugate,
would be a selective disadvantage because it would remove
a beneficial adaptation. Again, a barrier to antibiotic resistance. Going back to the actual delivery,
the way that this would work, the donor bacterium
will transfer a plasmid, which is a circular piece
of DNA, in general, and the plasmid would contain
the artificial gene. And then, once the donor transfers
the plasmid to the recipient, it enters the recipient
and activates the artificial gene based on a pathogen specific promoter. That is a promoter that only
a certain type of bacteria, in any pathogen you choose to target,
would be able to activate. And then, the recipient pathogen
would be in to produce the anti-microbial polypeptide,
and it would kill off the recipient. To accomplish this,
I chose the RK2 plasmid, which is a broad host range
conjugative plasmid. That is a plasmid, as I mentioned, a circular piece of DNA that is capable
of synthesizing all the necessary proteins to transfer itself between bacteria. It can transfer itself
between many different types of bacteria so it can transfer itself exponentially, going from a small group of bacteria
to several more and several more, etc., until it spreads throughout a population. One more thing I’d like to mention
is that even if resistance did develop, there is promise in using artificial
selection to counter that resistance. And the way that this would work is
many variations of the artificial genes or the RK2 plasmid could be created
by artificially mutating them. And then, tested simultaneously
against the resistance bacteria. Hopefully, one would soon be able to find a variation which was again able to act
against the resistance bacteria, thus overcoming the resistance
in a sort of co-evolution fashion. So let’s bring this all together. The way that this would work is that donor bacteria could be
transferred to the site of an infection. Then they would transfer the RK2 plasmid containing the artificial gene
to your indigenous microbiota, the normal, good bacteria in your body. These bacteria would then
spread it through their population, before transferring the artificial gene
to the pathogens, where the pathogen specific promoter
would activate the expression of the artificial gene, producing
the anti-microbial polypeptides and killing off the pathogens. (Applause) Earth. (Laughter) Let’s bring it all the way back out.
It’s a beautiful place to live. We’d all very much like
to continue living here. And I hope that my idea can contribute
to our continued survival on this planet. It’s important to know that ideas in general can be used
in new and different ways to push forward the future
and to make the world a better place. Even if those ideas might sound
a little bit crazy at first, or even if, the idea comes
from a high school student. Thank you. (Applause)

10 Replies to “Deploying artificial genes to overcome antibiotic resistance | Logan Collins | TEDxMileHigh”

  1. Listed now as an undergraduate at Dartmouth College working in lab of a Professor of Microbiology & Immunology. Good… I hope he has a fantastic career!

  2. In USA 80% of all antibiotics are used in animal agriculture. 11% of all antibiotics are used in pets and only 9% antibiotics are used in humans. So animal agriculture is responsible for most of antibiotic resistance.
    Solution is ban use of antibiotic in animals. And go vegan

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