[toufka]

This is the 'spot' where you put the ink in your 3D atom printer.

Life had used its entire 'ANSI-code' for its own purposes, (naturally (literally)). But if we want to insert our own stuff, we need a place to put it. So these guys refactored the entire code of e. Coli to avoid one of the lesser used characters, which can then be used as an escape character for any new code you want to use. Basically, refactoring an old ASCII program (e. Coli (20 amino acids)) to allow compatibility with UTF-8 (modern chemistry (~unlimited amino acids)) by shifting all uses of one of the letters to a compatible, but not identical case. And now you can use that letter for anything you like (when designing proteins).

You get to use new amino acids in building your proteins. The current amino acids have been evolutionarily defined by being metabolically creatable, useful, etc. and are restricted in number. Some get modified after the fact, but in general, there are only a limited number of amino acids used to build proteins. (Protein = biological machine)

If you have an 'escape character' in your DNA, you can insert any amino acid you want into that protein by registering it in that empty spot. This can include introducing amino acids you created chemically in a lab. So now your new organism can start to use amino acids in its proteins that are impossible to build in nature. Creativity gets opened wide. Right-handed amino acids are the obvious choice to start with - biologically 'inert' (immune system doesn't recognize them), but functionally identical. Theoretically you could start to use non-organic atoms. New biologically orthogonal reactive groups. Or entirely new structural features.

You can now incorporate non-natural chemical moieties with atomic resolution.