Protein and nucleotide deglycase that catalyzes the deglycation of the Maillard adducts formed between amino groups of proteins or nucleotides and reactive carbonyl groups of glyoxals. Thus, functions as a protein deglycase that repairs methylglyoxal- and glyoxal-glycated proteins, and releases repaired proteins and lactate or glycolate, respectively. Deglycates cysteine, arginine and lysine residues in proteins, and thus reactivates these proteins by reversing glycation by glyoxals. Is able to repair glycated serum albumin, collagen, glyceraldehyde-3-phosphate dehydrogenase, and fructose biphosphate aldolase. Acts on early glycation intermediates (hemithioacetals and aminocarbinols), preventing the formation of Schiff bases and advanced glycation endproducts (AGE) that cause irreversible damage. Also functions as a nucleotide deglycase able to repair glycated guanine in the free nucleotide pool (GTP, GDP, GMP, dGTP) and in DNA and RNA. Is thus involved in a major nucleotide repair system named guanine glycation repair (GG repair), dedicated to reversing methylglyoxal and glyoxal damage via nucleotide sanitization and direct nucleic acid repair. However, is less efficient than Hsp31 and YhbO, suggesting that YajL might be preferentially dedicated to protein repair. Displays a covalent chaperone activity with sulfenylated thiol proteins by forming mixed disulfides with members of the thiol proteome, and preferentially with sulfenylated cellular proteins, upon oxidative stress; these mixed disulfides can be subsequently reduced by low-molecular-weight thiols to regenerate YajL and reduced proteins. Involved in biogenesis of ribosomal proteins, probably as a ribosomal protein-folding chaperone. Confers resistance to oxidative stress. Plays an important role in protection against electrophile/carbonyl stress. The chaperone activity reported for YajL is probably recruited to execute its deglycase activity, to interact with non-native glycated proteins and gain access to partially buried glycated sites. Also displays an apparent glyoxalase activity that in fact reflects its deglycase activity.
