Chemical and biological photoswitches

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***We aim to develop general ways to control protein function using light. In so doing, we make new photoswitchable molecules and learn how to couple these to proteins to drive functional transitions. We explore how natural photo-proteins can evolve new function and we develop in vitro evolution and selection methods to generate tools for chemical biology.******We are taking two general approaches to achieve these goals. The first is a 'bottom-up' approach starting with the chromophore and designing photo-proteins de novo. We propose to modify the chromophore azobenzene, which can be reversibly switched between trans and cis states by light, so that it switches with near-infrared light. A near-IR switchable azobenzene core would enable advances in photopharmacology, biomedical engineering and drug delivery. We aim to find general ways to attach azobenzene-based switches to proteins to control protein folding and thereby function. We will use a combinatorial approach to find azobenzene based cross-linkers and cross-linking sites that permit photo-control of fynomers, which are small antibody alternatives. In parallel, we will test a novel bio-orthogonal labelling approach for targeting intracellular proteins, where thiol-based cross-linking is complicated by the presence of glutathione.******Our second approach starts with a naturally-occurring photo-proteins, explores how these work and tries to engineer them as elements for driving change in other proteins. In the process of re-engineering natural photo-proteins, we discovered remarkable light-induced structural transitions including domain swapping and beta-strand slippage. These light-driven phenomena reveal surprising fundamental features of protein dynamics. We aim to test where duplication of a beta strand is generally tolerated in beta-sheets and how often this can lead to new function. Finally, we will explore new phage display technologies to select and evolve photo-proteins.*****