Novel glyoxalases from Arabidopsis thaliana

Abstract

We examined six Arabidopsis thaliana genes from the DJ-1/PfpI superfamily for similarity to the recently characterized bacterial and animal glyoxalases. Based on their sequence similarities, the six genes were classified into two sub-groups consisting of homologs of the human DJ-1 gene and the PH1704 gene of Pyrococcus horikoshii. Unlike the homologs from other species, all the A. thaliana genes have two tandem domains, which may have been created by gene duplication. The six AtDJ-1 proteins (a-f) were expressed in Escherichia coli for enzymatic assays with glyoxals. The DJ-1d protein, which belongs to the PH1704 sub-group, exhibits the highest activity against methylglyoxal and glyoxal, and K m values of 0.10 and 0.27 mM were measured for these two substrates, respectively, while the corresponding k cat values were 1700 and 2200 min À1 , respectively. The DJ-1a and DJ-1b glyoxalases exhibited higher specificity towards glyoxal. The other three proteins have either no or extremely low activity for glyoxals. For the DJ-1d enzyme, the residues, Cys120/313 and Glu19/212 at the active site and His121/314 and Glu94/287 at the oligomeric interface were mutated to alanines. As in other enzymes characterized to date, mutation of either the Cys or the Glu residues of the active site completely abolished enzyme activity, whereas mutation of the interface residues produced a variable decrease in activity. DJ-1d differs from its animal and bacterial homologs with respect to the configuration of its catalytic residues and the oligomeric property of the enzyme. When the wild-type DJ-1d enzyme was expressed in E. coli, the bacteria became resistant to glyoxals.

A Glutathione-independent Glyoxalase of the DJ-1 Superfamily Plays an Important Role in Managing Metabolically Generated Methylglyoxal in Candida albicans

“…Although the specific reason for these differences is unclear, our results indicate that Hsp31-like proteins are considerably more active methylglyoxalases than human DJ-1. This conclusion is consistent with a recent report on the glyoxalase activities of several A. thaliana members of the DJ-1 superfamily, which found that the closest homologs of human DJ-1 in that organism (AtDJ-1A and AtDJ-1B) have only modest glyoxalase activity (61). Therefore, it remains to be established if the glyoxalase activities of human DJ-1 and its close homologs are physiologically relevant.…”

New Arabidopsis thaliana Cytochrome c Partners: A Look Into the Elusive Role of Cytochrome c in Programmed Cell Death in Plants

“…Oxidative Stress-The glyoxalase system consists of two enzymes, GLY1 and GLY2, involved in methylglyoxal (MG) detoxification, though novel glyoxalases have been recently described (65). MG is produced in all living organisms and its levels in plants are enhanced on exposure to different abiotic stresses (66).…”

Identification of glutathione (GSH)-independent glyoxalase III from Schizosaccharomyces pombe

“…cDJR - 1.1 is found in both the nucleus and cytoplasm of the intestine, while cDJR - 1.2 is detected in various tissues and is only present in the cytoplasm [6]. The Arabidopsis thaliana genome has six DJ - 1 genes, among which AtDJ - 1d encodes an enzyme that has the highest GLO3 activity [46]. Besides, a close homolog of HsDJ-1 called SpDJ-1 (Accession number: SPAC22E12.03c) has been found in the fission yeast Schizosaccharomyces pombe [41].…”