Murtagh, O. L. | Search bioRxiv

bioRxiv2026

In Cellulo pharmacological profiling and genomic editing reveals paralog-specific targets for PA generation during PLC signaling

Phosphatidic acid (PA) is an essential intermediate generated during phospholipase C (PLC) signaling, but its regulation is complex. PA can be generated by ten different diacylglycerol kinase paralogs (DGKs) and two different phospholipase D paralogs (PLDs) in mammals. Because these enzymes are activated under diverse conditions and at various membranes, understanding paralog-specific contributions to PA production is critical for therapeutic development of drugs that modulate the PLC pathway. To address this, we aimed to characterize the paralog specificity of the DGK inhibitors R59022 and BMS-502 against individual endogenously-tagged DGK paralogs in live cells. We found that R59022 and BMS-502 both recruited endogenous DGKalpha to the plasma membrane, and inhibited the catalytic fragment of DGKalpha when ectopically localized to the mitochondrial outer membrane. However, at its effective dose, R59022 paradoxically increased PA levels, while BMS-502 functioned as a potent inhibitor. Live-cell imaging experiments using BMS-502 with carbachol stimulation of endogenous muscarinic receptors showed that inhibition of both DGKalpha and the PLDs is needed to substantially reduce PA levels during PLC activation. Our findings both identify paralog-specific druggable targets for modulating PLC signaling events, and establish a new platform for characterizing DGK and PLD activity in living cells.

biochemistry↗

bioRxiv2025

A Chemoproteomic Atlas of the Human Purine Interactome for Regioselective Ligand Discovery

Purines are essential bioactive molecules that interact with a large fraction of the human proteome. Despite their importance, the scope of actionable purine-binding pockets for ligand discovery remains limited. Here, we developed a quantitative chemoproteomics platform using sulfonyl-purine (SuPUR) chemistry to produce a massive and functional map of the human purine interactome. The SuPUR platform captured 31,000+ targetable tyrosine and lysine sites, representing the most comprehensive beyond cysteine chemoproteomics database for enabling protein ligand discovery. SuPUR ligands that bind through a regioselective fashion serve as enabling starting points for developing potent (nanomolar) and proteome-wide-selective modulators of enzymatic and protein-protein interaction function. Phenotypic screening identified a site-specific (Y237) and regioselective SuPUR ligand of ACAT2 to reveal an unexpected metabolic dependency in cancer cells. A crystal structure of SuPUR ligand-bound ACAT2 revealed the purine group binds deep in the CoA pocket forming key interactions with catalytic residues via a water bridge to guide future structure-based ligand design.

biochemistry↗