Leukippos InstituteCharacterizing bacterial gene circuit dynamics with optically programmed gene expression signals
Evan J Olson, Lucas A Hartsough, Brian P Landry, Raghav Shroff & Jeffrey J Tabor
"Gene circuits are dynamical systems that regulate cellular behaviors, often using protein signals as inputs and outputs. Here we have developed an optogenetic 'function generator' method for programming tailor-made gene expression signals in live bacterial cells. We designed precomputed light sequences based on experimentally calibrated mathematical models of light-switchable two-component systems and used them to drive intracellular protein levels to match user-defined reference time courses. We used this approach to generate accelerated and linearized dynamics, sinusoidal oscillations with desired amplitudes and periods, and a complex waveform, all with unprecedented accuracy and precision. We also combined the function generator with a dual fluorescent protein reporter system, analogous to a dual-channel oscilloscope, to reveal that a synthetic repressible promoter linearly transforms repressor signals with an approximate 7-min delay. Our approach will enable a new generation of dynamical analyses of synthetic and natural gene circuits, providing an essential step toward the predictive design and rigorous understanding of biological systems."http://bit.ly/OipvLb
comment:Rice synthetic biologists shine light on genetic circuit analysis
"Bioengineers invent ‘light tube array,’ ‘bioscilloscope’ to test, debug genetic circuits
In a significant advance for the growing field of synthetic biology, Rice University bioengineers have created a toolkit of genes and hardware that uses colored lights and engineered bacteria to bring both mathematical predictability and cut-and-paste simplicity to the world of genetic circuit design.
“Life is controlled by DNA-based circuits, and these are similar to the circuits found in electronic devices like smartphones and computers,” said Rice bioengineer Jeffrey Tabor, the lead researcher on the project. “A major difference is that electrical engineers measure the signals flowing into and out of electronic circuits as voltage, whereas bioengineers measure genetic circuit signals as genes turning on and off.”
In a new paper appearing online today in the journal Nature Methods, Tabor and colleagues, including graduate student and lead author Evan Olson, describe a new, ultra high-precision method for creating and measuring gene expression signals in bacteria by combining light-sensing proteins from photosynthetic algae with a simple array of red and green LED lights and standard fluorescent reporter genes. By varying the timing and intensity of the lights, the researchers were able to control exactly when and how much different genes were expressed.
“Light provides us a powerful new method for reliably measuring genetic circuit activity,” said Tabor, an assistant professor of bioengineering who also teaches in Rice’s Ph.D. program in systems, synthetic and physical biology. “Our work was inspired by the methods that are used to study electronic circuits. Electrical engineers have tools like oscilloscopes and function generators that allow them to measure how voltage signals flow through electrical circuits. Those measurements are essential for making multiple circuits work together properly, so that more complex devices can be built. We have used our light-based tools as a biological function generator and oscilloscope in order to similarly analyze genetic circuits.”
Video:http://bit.ly/1qtAEaY #synbio #syntheticbiology