American Chemical Society
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Discovering Selective Binders for Photoswitchable Proteins Using Phage Display

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posted on 2018-09-11, 00:00 authored by Jakeb M. Reis, Xiuling Xu, Sherin McDonald, Ryan M. Woloschuk, Anna S. I. Jaikaran, Frederick S. Vizeacoumar, G. Andrew Woolley, Maruti Uppalapati
Nature provides an array of proteins that change conformation in response to light. The discovery of a complementary array of proteins that bind only the light-state or dark-state conformation of their photoactive partner proteins would allow each light-switchable protein to be used as an optogenetic tool to control protein–protein interactions. However, as many photoactive proteins have no known binding partner, the advantages of optogenetic controlprecise spatial and temporal resolutionare currently restricted to a few well-defined natural systems. In addition, the affinities and kinetics of native interactions are often suboptimal and are difficult to engineer in the absence of any structural information. We report a phage display strategy using a small scaffold protein that can be used to discover new binding partners for both light and dark states of a given light-switchable protein. We used our approach to generate binding partners that interact specifically with the light state or the dark state conformation of two light-switchable proteins: PYP, a test case for a protein with no known partners, and AsLOV2, a well-characterized protein. We show that these novel light-switchable protein–protein interactions can function in living cells to control subcellular localization processes.