Human DJ-1 is a genetic cause of early-onset Parkinson's disease (PD), although its biochemical function is unknown. We report here that human DJ-1 and its homologs of the mouse and Caenorhabditis elegans are novel types of glyoxalase, converting glyoxal or methylglyoxal to glycolic or lactic acid, respectively, in the absence of glutathione. Purified DJ-1 proteins exhibit typical Michaelis–Menten kinetics, which were abolished completely in the mutants of essential catalytic residues, consisting of cysteine and glutamic acid. The presence of DJ-1 protected mouse embryonic fibroblast and dopaminergically derived SH-SY5Y cells from treatments of glyoxals. Likewise, C. elegans lacking cDJR-1.1, a DJ-1 homolog expressed primarily in the intestine, protected worms from glyoxal-induced death. Sub-lethal doses of glyoxals caused significant degeneration of the dopaminergic neurons in C. elegans lacking cDJR-1.2, another DJ-1 homolog expressed primarily in the head region, including neurons. Our findings that DJ-1 serves as scavengers for reactive carbonyl species may provide a new insight into the causation of PD.
Bacterial heat-labile (LT) enterotoxins signal through tightly regulated interactions with host cell gangliosides. LT-IIa and LT-IIb of Escherichia coli bind preferentially to gangliosides with a NeuAcα2-3Galβ1-3GalNAc terminus, with key distinctions in specificity. LT-IIc, a newly discove ... more
Phosphate deficiency is characteristic for many natural habitats, resulting in different physiological responses in plants and bacteria including the replacement of phospholipids by glycolipids and other phosphorous-free lipids. The plant pathogenic bacterium Agrobacterium tumefaciens, whi ... more
A tryptophan side chain was introduced into subsite +1 of family GH-18 (class V) chitinases from Nicotiana tabacum and Arabidopsis thaliana (NtChiV and AtChiC, respectively) by the mutation of a glycine residue to tryptophan (G74W-NtChiV and G75W-AtChiC). The specific activity toward glyco ... more