Tideglusib Identified as First Chemical Probe for NatA Acetyltransferase via Novel Covalent Mechanism
- NatA catalyzes a large share of eukaryotic Nα-acetylation, a co-translational modification important for protein stability, localization and function; no validated small-molecule NatA probe had previously been reported.
- Screening an in-house ~700-compound library and optimizing a thiadiazolidinedione scaffold identified tideglusib (YD3139) — a clinical-stage GSK-3β inhibitor — as a hit, repurposing a known drug toward NatA.
- Mechanistic studies showed tideglusib first binds NatA allosterically, after which CoA released during catalysis chemically modifies it into a reversible covalent adduct, a previously undescribed catalysis-dependent inhibition mechanism.
- The compound showed low-micromolar potency against yeast and human NatA with good selectivity over other NAT family members, and proteomics confirmed on-target activity in yeast cells, validating it as a mechanistic chemical probe.
What earns this a second look is the mechanism: an allosteric binder that stays non-covalent until the enzyme's own turnover releases CoA to staple it in place — a genuinely new trick, not just another warhead. Whether it generalizes beyond NatA's odd CoA-release chemistry is unclear, but it's worth filing away as a template for other CoA- or cofactor-dependent enzymes. The selectivity over other NATs despite a conserved active site is the more actionable lesson: skip the catalytic pocket, go allosteric, and you dodge the conservation problem for free. As probe discovery, repurposing tideglusib beats de novo synthesis for speed, but it also means every existing GSK-3β dataset on this molecule is now confounded — nobody should read across to NatA biology from tideglusib phenotypes without new chemical matter. NatA itself looks like a legitimate, underexplored target; this is a probe paper, not a drug paper, but it's the right first step.