Acetylation of YajL Preserves Its Protective Enzymatic Activity against Stress-Induced Glycolytic Byproducts

The E. coli protein YajL and its human homologue DJ-1 catalyze the inactivation of reactive carbonyl species that result from high glycolysis rates. Left unchecked, these reactive carbonyl species have the potential to induce protein damage. Proteomics studies have shown that YajL is post-translationally acetylated at lysine 142 when glycolytic rates are high, but the functional significance of this modification is unclear. To determine the impact of acetylation on YajL activity, we cotranslationally incorporated acetylated lysine into YajL using genetic code expansion and conducted kinetic activity assays. We found that acetylated YajL retains function and may possess kinetic advantage over the unmodified form. Additionally, we found that lysine 142 is susceptible to modification by a reactive carbonyl substrate that YajL targets, but acetylation of this residue prevents this potentially damaging modification.