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Comment by xg15 | Hacker News Reader

Out of curiosity: We seem to have a very good understanding how synthesis in biological processes works (from DNA to the eventual molecules), we are able to create DNA/RNA molecules with arbitrary content and we're increasingly able to simulate what molecule a particular nucleotide sequence would produce.

So, putting the three together, would it be possible to use actual biosynthesis for designed molecules by basically writing your own DNA/RNA and inserting it into a cell?

(Or is this already what's being done?)

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in theory it's possible, in practice it's not. DNA encodes the information on how to produce to proteins. Proteins can catalyze chemical reactions. But there's no straightforward to look at a nucleotide sequence and figure out what it's corresponding protein does. Nor can we design proteins with arbitrary functions.

The entire thing is so unimaginably complex. For example, for a lot proteins that are catalysts (aka enzymes) the actual catalytic part is a metal ion and the protein mostly provides scaffolding. A nucleotide sequence alone doesn't directly tell you what ion is needed. In some cases, multiple ions can fit, but only one actually results in the protein work. This the basis for how a lot of toxic metal exert their toxic effects.

It's also not as simple as a nucleotide sequence codes for a protein and that's it. Proteins fold into their final shape from the chain of amino acids that DNA encodes. Protein folding in general is a hard problem. Biological proteins may have other proteins (called chperonins) that help them fold into their proper configuration. Then proteins may also be modified after they've folded (again by other proteins). Some proteins are made up of multiple sub-units as well.

Thanks a lot for the info.

> Proteins fold into their final shape from the chain of amino acids that DNA encodes. Protein folding in general is a hard problem.

My hope was that we had made progress in exactly that domain. Yes, the relationship between a nucleotide sequence and the resulting protein is extremely complex, but my impression was that we have tools to simulate the folding process for a given chain of amino acids (Folding@Home comes to mind).

So I was imagining a brute-force like process, where you (somehow) start with some candidate sequences, simulate how they would fold and use the sequence that comes closest to the molecule you wanted to have in the first place. Of course this only works if your target molecule can be assembled out of amino acids.

Transgenic goats have been produced which secrete drugs in their milk -- one transgenic female goat can produce about six pounds a year of human antithrombin, a blood thinner, in her milk.

From 2009: https://www.nytimes.com/2009/02/07/business/07goatdrug.html

Yes, this is already being done (since long) by many different research groups and industrial companies with various levels of ambition (it's normally not needed nor feasible to design everything completely from scratch though).

If you want an easily accessible jawdropping intro David Baker's youtube briefs here are pretty cool:

https://www.youtube.com/watch?v=ZrAwWx7meTk

I'm no expert, but I believe it's indeed what they're already doing: https://en.wikipedia.org/wiki/Genetically_modified_bacteria#...

But if I could make a guess I'd say that it in theory it might be relatively straightforward or easy to do but it's probably a lot harder in practice. That's often the case anyways.

Short answer: Yes

Long answer: No. It would be an incredibly complex undertaking.

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