Arylfluorosulfates Inactivate Intracellular Lipid Binding Protein(s) through Chemoselective SuFEx Reaction with a Binding Site Tyr Residue

Abstract

Arylfluorosulfates have appeared only rarely in the literature and have not been explored as probes for covalent conjugation to proteins, possibly because they were assumed to possess high reactivity, as with other sulfur(VI) halides. However, we find that arylfluorosulfates become reactive only under certain circumstances, e.g., when fluoride displacement by a nucleophile is facilitated. Herein, we explore the reactivity of structurally simple arylfluorosulfates towards the proteome of human cells. We demonstrate that the protein reactivity of arylfluorosulfates is lower than that of the corresponding aryl sulfonyl fluorides, which are better characterized with regard to proteome reactivity. We discovered that simple hydrophobic arylfluorosulfates selectively react with a few members of the intracellular lipid binding protein (iLBP) family. A central function of iLBPs is to deliver small-molecule ligands to nuclear hormone receptors. Arylfluorosulfate probe 1 reacts with a conserved tyrosine residue in the ligand-binding site of a subset of iLBPs. Arylfluorosulfate probes 3 and 4, featuring a biphenyl core, very selectively and efficiently modify cellular retinoic acid binding protein 2 (CRABP2), both in vitro and in living cells. The x-ray crystal structure of the CRABP2–4 conjugate, when considered together with binding site mutagenesis experiments, provides insight into how CRABP2 might activate arylfluorosulfates toward site-specific reaction. Treatment of breast cancer cells with probe 4 attenuates nuclear hormone receptor activity mediated by retinoic acid, an endogenous client lipid of CRABP2. Our findings demonstrate that arylfluorosulfates can selectively target single iLBPs, making them useful for understanding iLBP function.

Protein Glycosylation through Sulfur Fluoride Exchange (SuFEx) Chemistry: The Key Role of a Fluorosulfate Thiolactoside

“…In 2016, the coupling of a single polyethylene glycol fluorosulfate (PEG‐OSO 2 F) with the lysine residues of commercially available bovine serum albumin (BSA) was reported by Averick and co‐workers . In the same year, the Sharpless group demonstrated that PEG‐fluorosulfate derivatives can react chemoselectively with the phenolic hydroxyl of tyrosine residues within the binding site of intracellular lipid binding proteins and, more recently, that various aryl fluorosulfates show a similar reactivity toward other proteins . Therefore, no examples of protein functionalization by fluorosulfate derivatives of biomolecules (e.g., sugar and amino acids) are known to date.…”

Aryl Fluorosulfate Trapped Staudinger Reduction

“…Even though a fluorosulfate group was embedded in the azide substrate, only the substitution of the o -fluorosulfate on the phosphine moiety was enabled by proximity. 13 …”

The Application of Fluorine‐Containing Reagents in Structural Proteomics

“…AF probes are less reactive than the SF counterparts and preferentially modify lysine in protein pockets. [39] Recently, Jones and co-workers [40] found that 19 reacts with tyrosine and serine to generate products that lose water. Dehydration occurs by b-elimination following serine modification.…”