In this new approach to controlling molecular-scale life processes, which could eventually facilitate the production of biofuels
from microbes, and which the researchers detailed in an article in Nature Biotechnology
, gene expressions were started and stopped by light flashes controlled by a computer that learned through feedback to achieve and hold pre-set conditions, according to the BBC
This simple method worked to regulate a complex process because the commonly experimented upon Saccharomyces cerevisiae yeast used in this study was found in previous research to have light-switchable genes
-- its phytochrome
molecule, a photoreceptor protein
, switches to an active form in response to a red flash, then converts back in response to a deeper red flash, a reaction that can start or stop genes for specific proteins.
In this test, a feedback loop was completed by adding tracking "reporter" molecules that emitted florescent light while the yeast population expressed corresponding genes.
Lead author John Lygeros told the BBC the process was challenging experimentally -- far more complex than a simple on-off switch -- because it involved half a dozen chemical reactions, yet the team's computer model succeeded in tracking how long each light flash needed to last to maintain a precise amount of gene expression, and learned to regulate the ongoing process through the feedback loop.
"It's quite difficult to engineer synthetic circuits that do something robustly in the cell, and the hope is that by augmenting this with external signals, you can get them to behave better," Lygeros explained.