Characterization of the Escherichia coli YajL, YhbO and ElbB glyoxalases

The DJ-1 superfamily is a group of proteins that shares a similarity with the human DJ-1, known to be associated with Parkinson disease. Novel glyoxalase activity, converting alpha-oxoaldehydes to carboxylic acids, has been reported for DJ-1 homologs in humans, worms, plants and bacteria. The four Escherichia coli genes, hchA, yajL, yhbO and elbB, have been known to share sequence similarities and catalytic residues with other DJ-1 superfamily members. We investigated here whether they exhibit similar glyoxalase activity, as previously shown for HchA protein. Purified YajL, YhbO and ElbB exhibited glyoxalase activity with different substrate specificities, optimal pHs and metal effects. Overexpressions of the homologs enhance cellular protection from exogenously added glyoxals and reduce the glyoxal-dependent increase in intracellular advanced glycation end products. Based on their expression, primarily during the stationary phase, we speculate that their roles in cells as glyoxalases are manifested during the stationary phase.