Monday, November 7, 2011

Gene expression can be controlled with a computer

Combining a unique protein with computer-controlled rays of light, rendered scientists able to control gene expression in yeast. Because the micro-organism contains a light-sensitive protein called phytochrome, light pulses are able to modify its behaviour. A computer, that was programmed to produce red light, activated the phytochrome, which correspondingly lead to the onset of gene expression. The gene of interest was modified by the scientists, to contain a fluorescent label. Whenever this gene is translated into a protein, this would be marked by a detectable fluorescent label. By picking up the intensity of the fluorescent signal, the amount of protein that is being produced by the yeast is known, allowing the computer to be in full control over the process.

Phytochromes respond to red light, which change the shape of the protein, allowing it to perform its biological functions. In turn, the protein can be shut off by a bundle of deeper red light. Because the computer receives feedback about how much protein is produced, it is able to precisely control the process by turning phytochrome on and off.

By increasing or shortening the length of the light burst, the activity of the phytochrome can be altered. Scientists have developed a model that predicts how much protein will be formed by a certain time that the yeast is exposed to the red light. By attempting to control a yeast's genetic machinery with light, scientists hope to learn more about intracellular pathways that lead up to gene expression. We are interested in controlling these pathways to let micro-organisms do what we want. Controlling the production of a protein by light is an example of how we can exert control over a micro-organism, but there are many more methods being developed to alter the behaviour of organisms such as yeast and bacteria, to make them work for us.

This computerized method can be used in the production of drugs by the yeast. Scientists already have modified the micro-organism to let it produce proteins that are interesting to us, and the recently developed computer control can aid in the process. By tightly regulating the production, biotech companies gain more control over the compounds they produce. 

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