News & Events

Photocatalytic Proximity Labeling

Date: 
Thursday, March 4, 2021 - 13:00 to 14:00
Speaker: 
Dr. Jacob Geri
Affiliation: 
Princeton University
Event Category: 
Special Seminar
Location: 
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Abstract:

The spatial relationships between biomolecules define the structure of life. Consequently, new technologies that can reveal these relationships with increased precision deepen our understanding of biology and create avenues of inquiry which would be otherwise unavailable. Proximity-based labeling, in which chemically reactive tags are generated at a protein of interest and then label nearby biomolecules for MS-based identification, is a conceptually powerful way to leverage spatial relationships between proteins to discover protein-biomolecule interactions. Widely used proximity labeling technologies currently use enzymatically generated electrophilic biotin-AMP and phenoxyl radicals as reactive tags, which can undergo long-range diffusion in water and have limited spatial resolution. After a description of my graduate work in inorganic chemistry and organic methodology, I will describe the development of a new, higher resolution proximity labeling approach which instead uses more reactive biotin-carbene species incapable of diffusion through water, termed µMap. This technology uses antibodies conjugated to iridium-based photocatalysts to catalytically activate diazirines via Dexter energy transfer, converting them to carbenes which crosslink only to proteins that are adjacent to the antibody binding target. This technique was then used to label proteins colocalized with a variety of receptors on the surface of live lymphocytes, such as PD-L1, CD45, and CD300A, and was capable of distinguishing between receptor interactomes which could not be disentangled using traditional phenoxyl radical proximity labeling. Using small molecule probes in place of antibodies, the tight labeling radius enabled efficient chemoproteomic target ID and the identification of amino acids adjacent to their binding sites. This photocatalytic proximity labeling strategy is highly general, and represents a new level of spatial resolution in the discovery of protein-protein interactions.