Projects in the Woo group bridge chemistry and biology to reveal how small molecules influence proteins and drive biological outcomes.

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The human proteome consists of 20,000 proteins, yet less than 3% of these are “druggable” by a small molecule agent.  A central challenge in the expansion of the druggable proteome is the need to better define global small molecule–protein interactions.  By contrast, small molecules are essential mediators of native cellular processes [e.g., post-translational modifications (PTMs)], in addition to vehicles of human intervention (e.g., small molecule therapeutics).  Nature regulates the entire proteome through PTMs to protein regulatory hotspots that alter protein–protein interactions.  We are working to reveal natural allosteric regulatory hotspots for endogenous PTMs that are likewise modulated by exogenous small molecules.

To reveal this common ground, we use chemical biology approaches to map and manipulate small molecule interaction sites in the global proteome of live cells.  We developed a chemical proteomics platform to study the binding sites of exogenous small molecules to the global proteome, termed small molecule interactome mapping by photo-affinity labeling (SIM-PAL).  SIM-PAL uses a small molecule embedded with a diazirine and alkyne to capture and enrich binding sites to the whole cell proteome, which are structurally elucidated by mass-independent mass spectrometry.  We applied SIM-PAL to several non-steroidal anti-inflammatory drugs and revealed new stabilizing interactions within the global proteome. Close investigation of the underlying photo-chemistry within biomolecules will enable high-resolution structural insight to small molecule–protein interactions in a cellular context.  

In parallel, we developed a proximity-directed glycosyltransferase system for protein-specific introduction of an endogenous PTM, O-linked N-acetyl glucosamine (O-GlcNAc), in live cells.  We are applying our proximity-directed glycosyltransferase system to a series of proteins that carry high levels of O-GlcNAc during T cell activation in order to describe a function for some of the 2,000 O-GlcNAc sites mapped in primary human T cells.  As our efforts to map exogenous small molecule binding sites and manipulate endogenous PTMs progress, we anticipate the discovery of regulatory hotspots throughout the proteome and the small molecule influencers of protein–protein interactions.

Current projects:

Peering into the Cellular Black Box: We are combining chemical biology and mass spectrometry to reveal how small molecules interact with the proteome.

From Form to Function: We are engineering glycan stoichiometry on specific proteins to understand cellular signaling pathways during immunoactivation.

Gain of Function Natural Products: We are accessing unique chemical scaffolds to evaluate the regulation of protein interactions by novel mechanisms.