Discovering Selective Binders for Photoswitchable Proteins Using Phage Display

• Published in: ACS synthetic biology 2018-10, Vol.7 (10), p.2355-2364
• Main Authors: Reis, Jakeb M, Xu, Xiuling, McDonald, Sherin, Woloschuk, Ryan M, Jaikaran, Anna S. I, Vizeacoumar, Frederick S, Woolley, G. Andrew, Uppalapati, Maruti
• Format: Article
• Language: English
• ISSN: 2161-5063; 2161-5063
• DOI: 10.1021/acssynbio.8b00123

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.