One trillion photoswitchable molecular devices: a molecular foundry to control protein interactions using light

Lead Research Organisation: Imperial College London
Department Name: Dept of Chemistry

Abstract

The universal ability to control (bio)molecular interactions in living or synthetic systems is a grand challenge for chemical
biology, a solution for which would have wide-ranging implications for basic biology, synthetic biology and therapeutic
discovery. Photochemical control of biomolecular interactions is an approach to this challenge which has attracted intense
recent interest. Prominent examples range from photoresponsive materials to light-responsive protein domains, and
photoswitchable ligands which can control e.g. tubulin polymerization and thus cell division in response to light, also termed
photopharmacology (exemplified by recent papers from the Trauner and Feringa labs). Whilst these examples provide proof
of principle for the importance and potential of minimally invasive control of biology using light signals, they each suffer from
significant disadvantages, for example a requirement for genetic manipulation, or a highly bespoke design which works only
for a single highly engineered system.
Here we propose to overcome the limitations of existing paradigms by developing the first discovery platform for
photoswitchable ligands to any protein of interest, enabling a plethora of new approaches including on/off switches for
enzyme activity, protein-protein interactions, and protein localisation. Combining cutting-edge hyperstable photoswitch
technology (Fuchter) with trillion-member genetically encoded cyclic peptide library synthesis (Walport) we will generate a
toolkit for the identification of ligands which can bind to a given protein in one of two switchable configurations and
demonstrate its application to a series of light-switchable protein interactions (Tate). Furthermore, the modularity of these
molecular devices will enable their use as a component in future bottom-up and top-down synthetic biology approaches,
providing post-translational control over protein function in cells or protocells. The project will address the following Aims:
1) Design, synthesise and incorporate '1st generation' synthetic diazo photoswitches into a trillion-member cyclic peptide
library using flexible in vitro translation, and select binders to a model cell surface protein (cd59) .
2) Identify selective switchable ligands which can modulate binding to cd59 and induce switchable ligand uptake in a cellular
system in response to light-induced activation.
3) Expand the universal switchable ligand platform to exemplify applications in GPCR dimerisation (FFA2), reversible cell
capture, and multicyclic peptide libraries with switchable bridges.
Achievability & Remit: This project builds on
unique capabilities of the collaborating labs,
including flexible in vitro translation
technology for RNA display of trillion-member
cyclic peptide libraries (Walport), the
discovery of hyperstable photoswitches
(Fuchter) and innovations from current ICB
CDT students in the Tate group, including the
discovery of high-affinity (non-switchable)
cd59 ligands using large scale cyclic peptide
library screens (Bickel; with Bubeck lab), and
incorporation of cell-active photoswitches in
small molecule probes (Kounde; with GSK).
We thus have in place the sophisticated
technologies on which the physical science
innovations of this project will build, including
validated cyclic peptide libraries, robust
photoswitches, and access to a series of
model systems on which to test the PhysSci
innovations. The project directly addresses
the core ICB CDT remit, including molecular
interactions (protein/ligand, protein/protein)
and incorporation of novel devices into
multiscale biological frameworks, with
significant future applications in both
bioscience and synthetic biology.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/S023518/1 01/10/2019 31/03/2028
2277405 Studentship EP/S023518/1 01/10/2019 30/09/2023 Thomas Benjamin Jackson