Catching some rays

Alas, due to a disagreement between myself & Blogger as to how to timestamp things (and Blogger won), my initial post for the Week of Science has so far failed to show up there, despite my attempts to unstick it. From lemons shall come lemonade, in this case an extra post.

A key goal of synthetic biology is to transfer completely novel traits to organisms; doing so demonstrates an understanding of the trait and perhaps might be useful for something, though the latter is hardly essential.

Last week's PNAS advance publication site has a neat item (alas, requiring subscription for the text) showing how simple it can all be. By adding a single protein to E.coli the biology of E.coli is changed in a radical way.

There is something uniquely pleasurable about sitting in a sunbeam, since the plain glass window takes out the nasty UV. The Omics! Omics! director of ergonomics (responsible for preventing repetitive stress injuries by ensuring regular breaks from the keyboard) certainly likes a good sunbeam. But while the sunbeam provides me warmth and pleasure, it can't feed me.

E.coli is normally the same way; it knows not what to do with sunlight. But by stealing one little gene from another microorganism, Carlos Bustamante's group has changed that. Certain single celled organisms called archeans use light to drive a pump protein called bacteriorhodopsin. The pumping action creates a gradient of hydrogen ions, a gradient which can drive useful work. By moving bacteriorhodopsin to E.coli, the bacterium acquires the ability to generate energy from light of the correct wavelength. Indeed, because a respiratory poison was present the bacteria are now dependent on light for any energy production -- and since E.coli has a flagellum which can propel it, this energy production can be observed as light-dependent swimming.

As mentioned before, the paper requires a subscription, but the supplementary material does not. You can watch a movie of a tethered E.coli responding to light, with the false coloring indicating the wavelength being shown (red for stop, green for go of course!). Furthermore, the individual tethered cells can be treated like little machines and the forces they generate measured, from this important details of the molecular machinery can be worked out. Showy, yet practical!

[trying to push this through the Week of Science system too]