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Ivanic, J.

Publications and source records attributed to Ivanic, J..

2 recordsLinked to original sources
bioRxiv2023

Covalent inhibition by a natural product-inspired latent electrophile

Strategies to target specific protein cysteines are critical to covalent probe and drug discovery. 3-bromo-4,5-dihy-droxazole is a natural product-inspired, synthetically accessible electrophilic moiety that has previously been shown to react with nucleophilic cysteines in the active site of purified enzymes. Here we define the global cysteine reactivity and selectivity of a set of 3-bromo-4,5-dihydroxazole-functionalized chemical fragments using competitive chemoproteomic profiling methods. Our study demonstrates that 3-bromo-4,5-dihydroxazoles capably engage reactive cysteine residues in the human proteome and the selectivity landscape of cysteines liganded by 3-bromo-4,5-dihydroxazoles is distinct from that of haloacetamide electrophiles. Given its tem-pered reactivity, 3-bromo-4,5-dihydroxazoles showed restricted, selective engagement with proteins driven by interactions between a tunable binding element and the complementary protein sites. We further validate that 3-bromo-4,5-dihydroxazoles form covalent conjugates with glutathione S-transferase Pi (GSTP1) and peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (PIN1), emerging anti-cancer targets. Together, this study expands the spectrum of optimizable chemical tools for covalent ligand discovery and high-lights the utility of 3-bromo-4,5-dihydroxazole as a cysteine-reactive electrophile. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=57 SRC="FIGDIR/small/524242v1_ufig1.gif" ALT="Figure 1"> View larger version (15K): org.highwire.dtl.DTLVardef@13b987eorg.highwire.dtl.DTLVardef@1987ae1org.highwire.dtl.DTLVardef@1ab4fb9org.highwire.dtl.DTLVardef@1ff1f71_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗
bioRxiv2021

Protonation-Dependent Sequencing of 5-Formylcytidine in RNA

Chemical modification of cytidine in non-coding RNAs plays a key role in regulating translation and disease. However, the distribution and dynamics of many of these modifications remains unknown due to a lack of sensitive site-specific sequencing technologies. Here we report a protonation-dependent sequencing reaction for detection of 5-formylcytidine (5fC) and 5-carboxycytidine (5caC) in RNA. First, we evaluate how protonation combined with electron-withdrawing substituents alters the molecular orbital energies and reduction of modified cytidine nucleosides, highlighting 5fC and 5caC as reactive species. Next, we apply this reaction to detect these modifications in synthetic oligonucleotides as well as endogenous human tRNA. Finally, we demonstrate the utility of our method to characterize a patient-derived model of 5fC-deficiency, where it enables facile monitoring of both pathogenic loss and exogenous rescue of NSUN3-dependent 5fC within the wobble base of human mitochondrial tRNAMet. These studies showcase the ability of protonation to enhance the reactivity and sensitive detection of 5fC in RNA, and provide a molecular foundation for applying optimized sequencing reactions to better understand the role of oxidized RNA cytidine nucleobases in disease.

biochemistry↗