Orthogonal green and red light sensors have been constructed that operate in E. coli. When an image is projected on a lawn of bacteria, the sensors are able to record the image as a pattern of gene expression. We are using this as a platform to combine simple genetic circuits to reconstruct signal processing algorithms. The bacteria present the results of the computation to the user as a visible, printed output at a macroscopic scale. I will describe how this has inspired new computational methods to connect and optimize genetic circuits. This work will help elucidate the design principles by which simple genetic circuits can be combined to produce complex functions.

We have constructed an analogous light sensor that controls a protein-protein interaction in mammalian cells. Because protein-protein interactions are one of the most general currencies of cellular signaling, this system can be used to control diverse functions. I will show that this system can be used to precisely and reversibly translocate target proteins to the membrane with micrometer spatial resolution and second time resolution. The system has also been used to control the translocation of rho-family GTPases and their upstream activators. This enables light to be used to control the actin cytoskeleton to precisely reshape and direct cell morphology. The light-gated protein-protein interaction will be useful for the design of diverse light-programmable reagents, potentially enabling a new generation of quantitative perturbation experiments in cell biology.

Host: William Hlavacek, T-6 wish@lanl.gov