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I agree the article is light on substance, but for a layperson reading it, much of that preamble is probably necessary. Anyway, I don't think the idea is to generate completely random polypeptides. The analogy with the lego bricks sounds more like they're mixing and matching known protein domains. Proteins are made of subunits called domains, and these are relatively modular, in the sense that you can concatenate the sequences for multiple domains into a single polypeptide and reasonably often end up with a functional protein consisting of the desired domains tethered together. These are called fusion proteins. In this case, the lego analogy suggests that there is a range of domains that bind to different structures on the external surfaces of bacterial cells, and another range of domains that kill bacterial cells by different mechanisms. So, if you want to kill species X, you first find a binding domain A that binds X cells, and then find an enzymatic domain B that can kill X cells, and create a fusion. This fusion protein AB will now attach to X cells and then kill them. If species X evolves to change its shape so that A no longer binds, you find a new binding domain C that does, and create a CB fusion, which can go on killing the evolved X cells via the same mechanism. If X evolves immunity to B's mode of action, then you find a new enzymatic domain D with another mode of action and create fusion AD. Repeat as necessary. Obviously, the success of this method depends on how many binding and enzymatic domains are effective against a particular bacterial strain. I have no idea how many bactercins are known, but presumably there must be enough to give hope to the author of this article. |