Identification and Phenotypic Analysis of Two Glyoxalase II Encoding Genes from Saccharomyces cerevisiae,GLO2 and GLO4, and Intracellular Localization of the Corresponding Proteins

Abstract

We have isolated and characterized two genes coding for the glyoxalase II enzyme from Saccharomyces cerevisiae. The coding region of the GLO2 gene corresponds to a protein with 274 amino acids and a molecular mass of 31,306 daltons. The open reading frame of the GLO4 gene could be translated into a protein with 285 amino acids and a molecular mass of 32,325 daltons. The amino acid sequences of the deduced proteins are 59.1% identical and show high similarities to the sequence of the human glyoxalase II. When grown on either glucose or glycerol as a carbon source, a glo2 glo4 double deletion strain contains no glyoxalase II activity at all and shows no obvious phenotype during vegetative growth. However, this strain showed a similar high sensitivity against exogenous methylglyoxal as compared with a glyoxalase I-deficient strain. Whereas the GLO2 gene is expressed on both glucose and glycerol, the GLO4 gene is only active on glycerol. The active Glo2p protein is localized in the cytoplasm and the active Glo4p in the mitochondrial matrix. Heterologous expression of the full-length GLO2 coding region in Escherichia coli resulted in an active protein. However, to get an active Glo4p protein in E. coli, the putative mitochondrial transit peptide at the N-terminal end had to be removed by shortening the 5 end of the GLO4 open reading frame.

The Human Hydroxyacylglutathione Hydrolase (HAGH) Gene Encodes Both Cytosolic and Mitochondrial Forms of Glyoxalase II

“…Within the resolution of our experiments we were unable to detect proteins targeted by this signal within the intermembrane space. The sequence and cleavage site of the amino-terminal pre-sequence predicted by MitoProt (22) are consistent with mitochondrial matrix targeting (29,30), and this agrees with the matrix distribution of mitochondrial glyoxalase II in yeast (6).…”

“…The glyoxalase system removes significant amounts of MG and has been shown to be critical for growth in this situation (7). In yeast, one study reported a similar protective function during growth in glycerol-rich medium (8), whereas another has reported that the enzyme system only protects significantly against exogenous MG (6). In the latter study the contribution of glyoxalase I (encoded by a single gene GLX1) was demonstrated by gene knockout.…”

“…In plants and yeast both cytosolic and mitochondrial glyoxalase II play complementary roles in protection against the toxic effects of MG (6,14). It is possible that the mitochondrial enzyme hydrolyzes S-D-lactoylglutathione that has diffused or been transported into the mitochondrial matrix from the cytosol (12).…”

“…The glyoxalase system is ubiquitous throughout the eukaryotic and prokaryotic kingdoms (6). In microorganisms it has been straightforward to demonstrate a function.…”

Assessment of chronological lifespan dependent molecular damages in yeast lacking mitochondrial antioxidant genes

“…The functions of glyoxalases were proposed to be important in genome stability and other cellular damages because of their scavenging activity of cytotoxic methylglyoxal, which is a byproduct of glycolysis [33,34]. Glycation reactions of methylglyoxal with amino acids can induce oxidative stress [35].…”