Chirality Could Kill Us All, If We Let It

In our high school chemistry classes we all learn about chirality, the property of organic molecules in which two chemically identical molecules can have different structures that are mirror images of each other. This can lead to their exhibiting different properties, and one aspect of chirality is causing significant concerns in the field of synthetic biology. The prospect of so-called mirror organisms is leading to calls from a group of prominent scientists for research in the field to be curtailed due to the risks they would present.

Chirality is baked into all life; our DNA is formed of right-handed molecules while our proteins are left handed. The “mirror” organisms would reverse either or both of these, and could in theory be used to improve biochemical production processes. The concern is that these organisms would evade both the immune systems of all natural life forms, and any human defences such as antibiotics, thus posing an existential risk to life. It’s estimated that the capacity to produce such a life form lies more than a decade away, and the scientists wish to forestall that by starting the conversation early. They are calling for a halt to research likely to result in these organisms, and a commitment from funding bodies not to support such research.

Warnings of the dangers from scientific advances are as old as science itself, and it’s safe to say that many such prophecies have come from dubious sources and proved not to have a basis in fact. But this one, given the body of opinion behind it, is perhaps one that should be heeded.

Header: Original: Unknown Vector: — πϵρήλιο, Public domain.

24 thoughts on “Chirality Could Kill Us All, If We Let It

    1. Could be applied to anything, especially via an appeal to the most extreme edge cases (like the nuclear schoolboy above). Yet risk mitigation is still widely used to good effect. One might argue it’s the most common human endeavor.

      Like I don’t remember any cases of germ warfare for several decades. Well we did have that big one a few years ago but aside from that…

  1. Our immune systems will attack an inanimate object that doesn’t belong inside of us but supposedly it would not attack a reverse-chirality microbe?

    Sounds like yet-another ‘resurch is skary’ story.

    Remember, life is just about everywhere we look on and in the Earth. So… the grey goo scenario? It already happened and we ARE the grey goo.

    1. The immune system does a lot of specialization beyond “attack anything foreign”. Imagine a mirror version of Measles that makes the current vaccine useless. Or a mirror version of salmonella that is unaffected by antibiotics. These mirror diseases would probably have trouble thriving in our bodies in ways the regular microbes don’t but it’s not crazy to be worried.

    2. The “immune system attack” is not a kinetic attack, but a protein binding to another, and processing it.

      If the target is the wrong way, or have the wrong turns, immune system cannot bind to it, inactivate it or damage it. It’s basically impervious to the immune system. But the oxygen, water, and a lot of molecules on our bodies (and on plants, and everything) don’t have chirality, so this “wrontg chiralled bacterium” can use it, reproduce, and we cannot do anything about it.

      Someone says “radiation can kill us too,” and while correct, radiation can be contained: isolate the are, or drop a giant concrete casket on top of it. A “wrong-side” bacterium will spread, nothing can stop it, and there’s no giant concrete casket that can save us.

      1. Eh, it’ll be more complex than that. One function of the immune system is to flag anything which isn’t “my human”, so it doesn’t matter if the molecule is left or right-handed: it still isn’t you, so your immune system will flag it for attack, and some of the mechanisms of those attacks won’t care about chirality either. Case in point: most bacteria have peptidoglycan cell walls which include both D- and L-Alanine, and there are multiple ways to detect and deal with microbes based on the cell wall structure. Chirality isn’t new, there are enzymes around (including in humans) whose job is to flip a compound from one form to the other. The only novelty here is the majority replacement of these compounds with the mirror form.

        Some things will be affected. Alternative chirality will probably require very different protein structures, so you’ll need new monoclonal antibodies and some types of vaccines, and probably a lot of antibiotics won’t recognise their proteins/structures/whatever. That doesn’t mean you can’t create these for mirror organisms, you’d just need new ones.

        It could be medically bad, but there’s no reason to think they’ll be totally invisible to the immune system.

      2. Is it correct to say that no molecules of opposing chirality can chemically bind to one another? Because otherwise I’d assume that the immune system would simply start making new antibodies that correspond to the new pathogens, regardless of which way their proteins face.
        It isn’t a goal-oriented process; biology would simply throw stuff at the wall until something sticks to a surface protein. And any organism that fails to do it would die and be replaced by one that could.

        Granted, it would suck to be in the former category for possibly a long time (in human terms). I’m on team don’t-make-the-mirror-universe-germs, but I still have the question of chemical bonding. Chemistry isn’t my thing

  2. The humongous vast majority of microbial life and viruses that we come into contact every day are benign at worst or symbiotic at best. The disease causing ones are super rare by comparison.
    I guess in some dystopian future a huge bioreactor full of synthetic organisms next to a water supply gets damaged and we all die but but that seems pretty far off.
    In any case you could still put in a regular handed cell protein that responds to an antimicrobial of your choice, or just synthesize up the opposite hand version of said antibiotic anyway.
    Plus all the nonspecific germ killing stuff (heat, UV, bleach, etc) would still work anyway as well.
    I’m not panicking yet.

    1. The disease ones are rare now. Benign parasitism is almost always an ancient truce with something that used to be a debilitating disease. Producing a bunch of new organisms that don’t have this truce might be pretty nasty, at least for a while. Eventually life would adapt, which is to say everything that couldn’t adapt would die off.

      And it’s too much of an assumption imo that simply making the reverse-chirality antibiotic would work reliably.

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