Plants contain proteins subjected to conformational changes in direct response to light irradiation. Moieties of those proteins, like the LOV2 domain from the Avena sativa Phototropin1 can be used to introduce light-operated switches onto other functional proteins. In a recent letter to Nature, Yi Wu and colleagues (Carolina University) poked at the Stratagene Quickchange kit to obtain a constitutive active Rac protein that was coupled to the vegetable LOV2 light switch using an overlapping PCR approach. The result of such a cut and paste was genetically encoded into HeLa, HEK93 and MEF/3T3 cell lines. Then, by irradiating whole cells or even localized micro-spot on the cell surface, PA-Rac1 was sufficiently photo-activated to generate polarized cell movements. In other words, light was controlling the motility of living cells via photoactivable Rac. Structural studies indicate that the Rac-LOV2 interface can be engineered to cage other proteins. Engineering and Biology are getting married. If you are a kick ass engineer, consider hacking biology at Ginkgo BioWorks, they are hiring.
Wu, Y., Frey, D., Lungu, O., Jaehrig, A., Schlichting, I., Kuhlman, B., & Hahn, K. (2009). A genetically encoded photoactivatable Rac controls the motility of living cells Nature, 461 (7260), 104-108 DOI: 10.1038/nature08241