A light-sensitive drug remains inactive inside the body until a doctor shines a light on it, switching on its therapeutic effects only at the precise location needed. This research tackles a fundamental gap in photopharmacology: no one understands exactly how these light-responsive molecules change shape and bind to their protein targets when illuminated. Without that atomic-level picture, designing drugs with a large enough potency difference between their “on” and “off” states remains guesswork. The team will use X-ray free-electron lasers to capture real-time structural snapshots of a light-addressable inhibitor (LD162) binding to human N-myristoyltransferase (NMT), a protein implicated in fungal infections, malaria, rhinovirus, and cancer. Their preliminary work shows LD162 binds NMT with 6.5 nM affinity in its active form and is roughly 50-fold weaker when inactive. If successful, this fundamental science will reveal the dynamical rules for engineering better light-controlled inhibitors. That knowledge could eventually enable spatially precise therapies that spare healthy tissue, or chemical biology tools that probe protein function with light. The immediate outcome, however, is a deeper mechanistic understanding of how photochemistry and protein binding interact—knowledge that, like much fundamental structural biology, may underpin unexpected applications in medicine, agriculture, or personal care.
View original technical description
General overview We imagine a future where a patient is given a drug which is inactive until it is illuminated with light, allowing the precise and targeted treatment of tissues and organs, as described by the emerging area of ‘photopharmacology’. Even beyond new medicines, light-addressable molecules hold significant potential for precision chemical biology across many sectors (agrosciences, personal care, etc). However, there are currently important fundamental mechanistic questions in this field, which are on many technical levels. Here, we show that we have the ability to tackle such key mechanistic questions. To fully realise the success of photopharmacology, it is critical to achieve a large differential binding potency between the light-addressable forms. This would allow for high (light-controlled) specificity for binding and inhibition of a biological target with human health relevance. However, how the binding of the drug to the protein impacts the drug’s photochemistry, and how the structural changes of the drug upon illumination impacts the dynamics of binding and unbinding is not understood on a fundamental level. Gaining such understanding is now possible with advanced X-ray Free Electron Laser (XFEL) based time resolved crystallography and is the focus of this proposal. Biology and medical relevance The human N-myristoyltransferase (NMT) protein is an important drug target. From a therapeutic perspective, NMT is an interesting target for photopharmacology application. It is enzyme that transfers myristate (a 14C fatty acid residue) co-translationally from myristoyl coenzyme A (MyrCoA) to N terminal glycine residues labelling proteins for membrane association, protein-protein interactions or subcellular localisation. NMT has emerged as a target in a wide range of diseases, from fungal infections and malaria to rhinovirus infection and cancer. A light-addressable NMT inhibitor will allow for further insight into NMT biology, such as further elucidation of kinetics of myristate labelling of different substrates and/or changes in substrate subcellular location in a light-dependent fashion. In this application, we use NMT as a representative target and show exciting preliminary work and initial results on a designed and synthesised a light-addressable analogue (LD162). LD162 exhibits strong binding to NMT1 (KD = 6.5nM) in its ‘active’ form and is ~50 fold less active in its ‘inactive’ form. We also present our recent unpublished crystal structure of the NMT:LD162 complex, establishing the feasibility for pump-probe time resolved crystallography of the complex. This proposal will leverage this data to generate a full analysis of the time-resolved structural and energetic changes upon photochemical activation for LD162 and a range of newly designed analogues. Objectives Having developed a potent light-addressable inhibitor of NMT we are in a unique position to enter the next design and characterisation stages. We will combine the expertise of the van Thor group in time resolved serial crystallography and laser spectroscopy with the expertise of the Fuchter group in photopharmacology and synthesis. We will execute a series of time resolved XFEL experiments of crystals of the HsNMT1:LD162 complex. A strategy for the development and synthesis of next-generation compounds is proposed to allow us to fully study changes upon photochemical activation across a range of drug binding modes/potency. Thermodynamics and spectroscopy investigations will test all compounds, which, coupled with the structural data,will reveal the dynamical detail of the molecular interactions with the NMT active site.
Plain English summaries and category classifications on this site are generated by AI and may not perfectly reflect the original research.
Is something wrong? Let us know