The apparent deglycase activity of DJ-1 results from the conversion of free methylglyoxal present in fast equilibrium with hemithioacetals and hemiaminals

Anna Andreeva, Zhanibek Bekkhozhin, Nuriza Omertassova, Timur Baizhumanov, Gaziza Yeltay, Mels Akhmetali, Daulet Toibazar, Darkhan Utepbergenov

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

Loss-of-function mutations in the gene encoding human protein DJ-1 cause early onset of Parkinson's disease, suggesting that DJ-1 protects dopaminergic neurons. The molecular mechanisms underlying this neuroprotection are unclear; however, DJ-1 has been suggested to be a GSH-independent glyoxalase that detoxifies methylglyoxal (MGO) by converting it into lactate. It has also been suggested that DJ-1 serves as a deglycase that catalyzes hydrolysis of hemithioacetals and hemiaminals formed by reactions of MGO with the thiol and amino groups of proteins. In this report, we demonstrate that the equilibrium constant of reaction of MGO with thiols is ~500 M- 1 at 37 °C and that the half-life of the resulting hemithioacetal is only 12 s. These thermodynamic parameters would dictate that a significant fraction of free MGO will be present in a fast equilibrium with hemithioacetals in solution. We found that removal of free MGO by DJ-1's glyoxalase activity forces immediate spontaneous decomposition of hemithioacetals due to the shift in equilibrium position. This spontaneous decomposition of hemithioacetals could be mistaken for deglycase activity of DJ-1. Furthermore, we demonstrate that higher initial concentrations of hemithioacetals are associated with lower rates of DJ-1-mediated conversion of MGO, ruling out the possibility that hemithioacetals are DJ-1 substrates. Experiments with CRISPR/ Cas-generated DJ-1- knockout HEK293 cells revealed that DJ-1 does not protect against acute MGO toxicity or carboxymethylation of lysine residues in cells. Combined, our results suggest that DJ-1 does not possess protein deglycase activity.

Original languageEnglish
Pages (from-to)18863-18872
Number of pages10
JournalJournal of Biological Chemistry
Volume294
Issue number49
DOIs
Publication statusPublished - Jan 1 2019

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Fingerprint

Dive into the research topics of 'The apparent deglycase activity of DJ-1 results from the conversion of free methylglyoxal present in fast equilibrium with hemithioacetals and hemiaminals'. Together they form a unique fingerprint.

Cite this