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We report a quantitative chemoproteomic approach that utilizes a clickable photoreactive probe for global profiling of celastrol targets, which may significantly improve the current understanding of celastrol's mode of action. [ABSTRACT FROM AUTHOR]

Selective profiling of steviol-catalyzing UDP-glycosyltransferases in plants was accomplished with a probe metabolically synthesized from two substrate-derived components comprising an alkynylated sugar receptor (steviol) module and a diazirine-modified sugar donor (UDP-glucose) module, thereby illustrating a facile approach for harnessing biosynthetic enzymes of natural glycosides in plants for synthetic biology. [ABSTRACT FROM AUTHOR]

Chemoselective and affinity-based probes of steviol were applied to the discovery of glycosyltransferase activity and corresponding UDP-glycosyltransferase in Arabidopsis thaliana, which illustrates a simple strategy for rapidly harnessing minable novel biological parts from plants for synthetic biology. [ABSTRACT FROM AUTHOR]

CD147 is a glycosylated transmembrane protein highly expressed on the surface of various tumor cells which plays vital roles in tumor invasion, progression and metastasis. We report the discovery of the natural product pseudolaric acid B (PAB) directly targeting CD147 by chemical proteomics utilizing a PAB-derived photoaffinity probe which could serve as a novel type of anticancer reagent. [ABSTRACT FROM AUTHOR]

Gambogic acid has shown significant potential as an anti-cancer and anti-inflammatory compound; however, the molecular mechanism underlying the actions of gambogic acid, particularly its cellular target profiles, has not been investigated. In this study, we report the proteome-wide profiling of potential cellular targets of gambogic acid using quantitative mass spectrometry-based chemical proteomics. The target profiles of gambogic acid in living HeLa and K562 cells were identified, which strengthened our understanding of the mode of actions of the phytochemical. [ABSTRACT FROM AUTHOR]

Human milk oligosaccharides (HMOs) are a family of unconjugated soluble glycans found in human breast milk that exhibit a myriad of biological activity. While recent studies have uncovered numerous biological functions for HMOs (antimicrobial, anti-inflammatory & probiotic properties), the receptors and protein binding partners involved in these processes are not well characterized. This can be attributed largely in part to the low affinity and transient nature of soluble glycan-protein interactions, precluding the use of traditional characterization techniques to survey binding partners in live cells. Here, we present the use of synthetic photoactivatable HMO probes to capture, enrich and identify HMO protein targets in live cells using mass spectrometry-based chemoproteomics. Following initial validation studies using purified lectins, we profiled the targets of HMO probes in live mouse macrophages. Using this strategy, we mapped hundreds of HMO binding partners across multiple cellular compartments, including many known glycan-binding proteins as well as numerous proteins previously not known to bind glycans. We expect our findings to inform future investigations of the diverse roles of how HMOs may regulate protein function., Competing Interests: There are no conflicts to declare, (This journal is © The Royal Society of Chemistry.)

Celastrol, isolated from the traditional Chinese medicinal herb Tripterygium wilfordii Hook. f. (Thunder God's Vine), has been used to treat cancer, chronic inflammatory, autoimmune and other human diseases. However, to date, the protein targets and the mechanism of action of celastrol have remained elusive. In this study, we find that celastrol can react with protein thiols in a unique covalent and reversible manner, while protein denaturing disrupts the interaction. Through a competitive chemoproteomics approach utilizing a cysteine-targeting activity-based probe, we report the proteome-wide quantitative profiling of cellular targets of celastrol in human cervical cancer HeLa cells. Representative targets are further validated via in vitro binding experiments and/or enzymatic activity assays. Bioinformatics analysis results suggest that celastrol exerts its numerous therapeutic effects through interaction with promiscuous proteins involved in various biological processes and cellular pathways.