The glyoxalase system in higher plants: Regulation in growth and differentiation

Abstract

Glyoxalases I and I1 have been studied and characterized in animals and in micro-organisms [ 11, but the work on glyoxalases in plants is still restricted to a few reports. Resides having a role in growth and development [ 1, 21, the enzymes help in the protection against ketoaldehyde toxicity [3, 41, as methylglyoxal, which is cytotoxic at high concentrations [S] is used as the substrate. Glyoxalases also affect microtubule assembly in cell-free systems [6] and are involved in vesicle mobilization [7, 81 and in various diseases [9-131 as well. Establishment of the presence of the glyoxalase system in plantsThe activity of glyoxalase I has been measured in a gymnosperm and a role for it in needle development has been suggested [ 141. Glyoxalase I and I1 levels were measured in Douglas Fir needles and calli. It was observed that a vigorously dividing system, like the callus, had more glyoxalase I and less methylglyoxal than a more quiescent system, like the needles, which had a very high methylglyoxal level and undetectable levels of glyoxalase I. Hesides glyoxalase I and 11, the level of methylglyoxal synthetase and reductase were measured as well in the same system. Methylglyoxal synthetase was detected in mature needles, while methyl reductase was present in young, dividing needles and in calli. It was suggested that it is the level of methylglyoxal and glyoxalase that controls proper needle development [ 141. W e have investigated the function and regulation of glyoxalase I in higher plants over the last few years. In 1983 we showed the presence of the enzyme in germinating pea seedlings [ 151. Later the enzyme activity was also detected in wheat, Datura, Brassica, Nicotiana and Amaranthus[ 16-181. The effect of various exogenous factors like temperature, pH, light, hormones, growth inhibitors, cell-division inhibitors and cell-division stimulators, that is, polyamines was studied in a number of plant systems. T o identify a source from which to purify the enzyme, a number of species of Brassica were screened for enzyme levels. B. juncea, B. oleracea, B. napus and B. carinata showed comparable activities while the activity was lower in B. nigra and B. campestris (Table 1). Interestingly it has been observed that the latter two mustard species are quite difficult to grow in in vitro cultures and it is possible that high levels of the enzyme make the other species easy to work with in vitro. The enzyme was purified to homogeneity from 7-dayold B. juncea [ 191. The enzyme migrated as a single band of 27 kDa on a 10% SDSIPAGE gel. W e have I993

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

“…The notion that the system could be involved in the regulation of cell proliferation (1,8,9) is not supported by our data as none of the deletion mutants showed a change in growth rate on either glucose or glycerol as sole carbon source. Maybe the system is important for survival under some still unknown physiological condition which leads to a much higher methylglyoxal level in the cell than present under "normal" growth condition.…”

Evidence for a role of exogenous glycinebetaine and proline in antioxidant defense and methylglyoxal detoxification systems in mung bean seedlings under salt stress

“…Methylglyoxal is produced in the plant cell during normal physiological processes (Deswal et al, 1993) and its level increased to a greater extent when plants get exposed to adverse environmental conditions including salinity, cold, drought and heavy metal stresses Singla-Pareek et al, 2006;Yadav et al, 2005a,b). Higher glyoxalase I activity might protect plants against MG that is formed during oxidative stress Jain et al, 2002, Veena et al, 1999.…”

Molecular characterization of glyoxalase-I from a higher plant; upregulation by stress

“…Furthermore, MG is enzymatically produced as a The nucleotide sequence data reported will appear in the GenBank, and DDBJ Nucleotide Sequence EMBL Databases under the accession number Z48183. byproduct of triose phosphate isomerase [22] and from DHAP by the methylglyoxal synthetase, an enzyme identified in various cells types, including plants [6]. Glyoxalase-I catalyzes the formation of S-D-lactoylglutathione (S-LG) from MG and GSH.…”

“…In addition, inhibitors of glyoxalase-I and -II induced growth arrest in tumoral cells [1,18]. In plants, increased glyoxalase-I activity has been found in dividing cells, like those from cell suspensions, calli, seedlings and root tips [6,19]. In soybean cell suspension glyoxalase-I was induced by auxin, with a peak of maximum activity that preceded cell division [19].…”