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If a user-specific venom managed to work by liquefying the phospholipid membranes of animal cells, how would it be produced? (It would act more like a venom in this case.)

By specific, I mean that the venom would work on all cells except the cells of the animal who produced it, even within an individual within a species:

  • animal 1 made it
  • animal 2 would die from it
  • animal 1's offspring would die from it
  • yet animal 1 is resistant

The problem is that to be released, it couldn't be moved out of the cell where it was produced (since it would destroy the cell) and couldn't be transported. What's more, if it was DNA specific, it would already have dissolved the cell before stopping. And to be resistant, the protein would have to become less effective (i.e, misfolding or denaturing itself so as not to further dissolve fats). The venom would have to be specific enough that no other organism could develop resistance to the venom.

How could such an acid-like substance be produced by a creature and be so specific, so that the individual member of the species would be the only one resistant?

The offspring of individual 1 would have their own variant that would kill their parents, and the variants of the parent would kill their offspring. The venom is not only DNA specific to common genotype characteristics but also to an individual. This, of course, is where the "magic" comes in since transporting the venom to the DNA of the individual cell wouldn't work. And using the mRNA strand that had the codons for the polypeptide chain form of the venom wouldn't work, since the venom itself is unchanging from individual to individual(it's just the resistance against the specific venom that changes from individual to individual), and scrambling the antigens on the protein won't work; this is an enzyme, not a surface-receptor protein.*

The "magic" part is that although the structure of the molecule is unchanging, it has this individual specificity. My problem is transporting the molecule out of the cell and without destroying it.

Gryphon
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FoxElemental
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  • you do realize many animals have digestive venom that would kill even themselves if they bit themselves. – John Apr 13 '18 at 13:29
  • Please clarify "the venom itself is unchanging from individual to individual" - if it is the same (same molecules) how would it be different (A is unharmed by Xa and can kill Bwith it, B is unharmed by Xb and can kill A with it makes sense, only if Xa!=Xb) – bukwyrm Apr 19 '18 at 12:55
  • Please don't make edits that change the question, instead ask them as new follow up questions (possibly linking back to this one). Otherwise existing answers get invalidated by the change. – Tim B Apr 26 '18 at 12:01

3 Answers3

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You would need to take a page from the AIDS virus, or from immunoglobulin development.

  1. Start with a toxin. Probably all individuals in this species have a similar base toxin.

  2. Scramble antigenic sites randomly on your version of the toxin. It is pretty cool, the way humans do this to generate diverse immunoglobulins capable of recognizing millions of different antigens. In short there is post-translational scrambling that goes on which adds random diversity. Read more! https://en.wikipedia.org/wiki/Antibody#Immunoglobulin_diversity

  3. Generate your own neutralizing antibodies to your self-version of the toxin.

Now you have a randomly scrambled toxin that you are immune to, but no-one else. The active site that works on membranes needs to be in some pocket not amenable to neutralization by immunoglobulin or others of your species can be immune to your toxin. Immunoglobulin binding needs to produce some sort of steric hindrance that prevents the toxin from acting.

The toxin would be treated like we treat pancreatic enzymes. Those enzymes are in us and dissolve meat and fat. They will dissolve us alive if given the chance: pancreatitis. They are kept inactivated and then activated right before being deployed into the gut.

A side effect to this system: if you get hit with someone else's toxin and live through it, you will be immune to that individual's toxin afterwards.

Willk
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  • This is an interesting idea for the larger problem of killing other individuals of your species, but seems to fall short of addressing OP's stated goal of something that will "work by liquefying the phospholipid membranes of animal cells". Sure alternatives are sometimes accepted, but it's nice if in the answer you at least address the fact that you aren't providing exactly what the OP asked for. :) – user Apr 11 '18 at 20:30
  • @MichaelKjörling - I understood the phospholipid mechanism to be a given - "if it managed to work that way" - and the question to be about individual specificity of a toxin. – Willk Apr 11 '18 at 22:16
  • @ Willk: Great idea except for one thing: this isn't a supercomplex surface receptor protein I'm keeping on cells, it's meant to be like an enzyme. Secondly, I haven't found a way to get past the issue of the enzyme dissolving the lipid membrane. And if the protein doesn't act, then it's binding site (where it destroys lipids) is blocked, and the protein is rendered useless. Do you have any idea how to get around this? – FoxElemental Apr 13 '18 at 20:38
  • You could have your membrane attack toxin function like the polymyxin antibiotics. https://en.wikipedia.org/wiki/Polymyxin They do what you want your toxin to do but it is not enzymatic - more like detergent. – Willk Apr 14 '18 at 20:59
  • The issue here being that not only would it not work as an enzyme, it would be ineffective (having cell walls, whether with peptidoglycan, cellulose, chitin, etc.) would block the effectivity of the enzyme. – FoxElemental Apr 15 '18 at 17:56
  • You specify in your OP that these are animal cells so cell walls are not an issue. Your active site is not supercomplex but the adjoining identity part of the molecule is - it needs to be to get the specificity you want. Individuals will have antibodies to the supercomplex region of their own toxin which clear it just as antivenin antibodies clear snake venoms. Individuals do not have antibodies to the supercomplex regions of other individual's toxin. – Willk Apr 18 '18 at 21:25
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I'm afraid not going to work that way, because the cell membrane does not contain DNA at all, so for a single molecule to work, the venom should have two different forms to begin with - one innocuous and one active. You'd need a protein with bistable folding, one form is inert, the other is lethal. This conformational change is triggered by a secondary group (what is called an effector chain), itself activated by a "reader" head that recognizes something. Either the DNA directly or some expression of same, e.g. membrane antigens.

The venom would have to act in some very complex way:

  • recognizing some loci on the cell membrane, and activating unless a very specific set of markers was also found. The first 'rule' avoids the venom expending itself activating at random, or far from any cell, the second implements the "target specific" part. This is more or less like the opsonisation process in the human immune system works - a "tag" is added to a target cell, then a venom (or a lymphocite) kills it. You'd be looking at essentially a rejection reaction.

  • the venom is actually part of the organism's immune system, and has a similar function as the major histocompatibility complex in humans: it triggers an immune reaction unless the organism recognizes it as "self". In a different organism, a sufficient quantity of venom would trigger the equivalent of a anaphylactic shock (or it could induce the organism to attack itself in a runaway autoimmune catastrophe).

  • the superprotein enters the cell and decodes enough DNA from the nucleus to determine that an activation is in order, and it has to be lethal. We're adding helicase capabilities to this little critter, which can't be so little anymore. This kind of venom could be a defense mechanism against mutations, e.g. cancer (you need a way to reprogram the system during pregnancy and in the newborn, of course). I had written an answer some time ago on how such a molecule could work. The trouble being that it could never have evolved by itself.

LSerni
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Immune system works based on some proteins expressed on the surface of the cells.

These proteins are highly specific, this is why organ transplant is bound to failure if no attentions are paid to choose highly compatible donors and immunosuppressors.

The same mechanism can be used with your venom: the molecule is embedded into a membrane which opens up as soon as it interacts with surface proteins of another cell, except those of the organism who produced the membrane.

Mind this is what normally our white cells do: attack all but our own cells.

This could also hint how to explain such a development: modified T-killer cells.

L.Dutch
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  • Hmmmm. So, using specific antigens? Surface receptors aren't a bad idea, but I still don't know how to get the synthesized venom out of the production cell, unless the cell died after producing a lot of this venom. I'm not sure how I feel about "suicide" cells, since this is meant for a creature that can produce lots of venom. I like the response you have in mind, though.(I study immunology) Not a bad idea. I'll keep that in mind and maybe combine it w/other answers. Thank you for your contributions. – FoxElemental Apr 19 '18 at 12:54
  • I wrote up a whole answer and then realized it's basically the same as your post... Ooops. Deleted. I'm a little baffled by the "venom out of the production cell" issue though. – MParm Apr 20 '18 at 22:40