Glutathione reductase from pea leaves: response to abiotic stress and characterization of the peroxisomal isozyme

Abstract

The glutathione reductase (GR; EC 1.6.4.2) isozyme present in peroxisomes has been purified for the first time, and its unequivocal localization in these organelles, by immunogold electron microscopy, is reported. The enzyme was purified c. 21-fold with a specific activity of 9523 units mg(-1) protein, and a yield of 44 microg protein kg(-1) leaves was obtained. The subunit size of the peroxisomal GR was 56 kDa and the isoelectric point was 5.4. The enzyme was recognized by a polyclonal antibody raised against total GR from pea (Pisum sativum) leaves. The localization of GR in peroxisomes adds to chloroplasts and mitochondria where GR isozymes are also present, and suggests a multiple targeting of this enzyme to distinct cell compartments depending on the metabolism of each organelle under the plant growth conditions. The expression level of GR in several organs of pea plants and under different stress conditions was investigated. The possible role of peroxisomal GR under abiotic stress conditions, such as cadmium toxicity, high light, darkness, high temperature, wounding and low temperature, is discussed.

Expression and enzyme activity of glutathione reductase is upregulated by Fe-deficiency in graminaceous plants

“…Similar expression patterns were observed for OsGR1 in that expression was mainly observed in root and calli, rather than in leaves (Kaminaka et al 1998). Conversely, the expression of PsGR2 was very low in root tissue and weak in shoots and flowers (Stevens et al 1997;Romero-Puertas et al 2006). These results suggest that the expression of graminaceous and non-graminaceous GR may be regulated differently.…”

“…These results suggest that the expression of graminaceous and non-graminaceous GR may be regulated differently. It has also been reported that the expression of PsGR1 and PsGR2 are regulated differentially in response to various stresses such as mechanical wounding and increased temperature (Romero-Puertas et al 2006). In barley, both HvGR1 and HvGR2 were upregulated by Fe-deficiency, whereas wheat exposed to the same conditions only exhibited increased levels of TaGR2 (Fig.…”

“…In plants, GR plays a key role in the response to oxidative stress by maintaining the intracellular pool of GSH. Expression of GR is upregulated under stresses such as changes in salinity, drought, high light intensity, mechanical wounding, chilling, and exposure to heavy metals and herbicides (Foyer et al 1991;Mullineaux and Creissen 1997;Apel and Hirt 2004;Romero-Puertas et al 2006). Iron (Fe) is an essential element in plants, and is required for cellular events such as respiration, chlorophyll biosynthesis, and photosynthetic electron transport.…”

Effects of leaf extracts on glutathione reductase expression, hydrogen peroxide and glutathione contents in the aquatic macrophyte Ceratophyllum demersum

“…The higher proportion of humic-like substances and aromaticity in oak extracts than reed extracts suggest humic-like substances might trigger the upregulation of GR, which ultimately enhances the re-conversion of GSSG to GSH required for various ROS-scavenging and detoxification mechanisms during oxidative stress (Romero-Puertas et al, 2006). Humic materials have been shown to induce significant transcriptional changes in the stress-related biotransformation enzymes, GST and cytochrome P450 (Menzel et.…”

Peroxisomal NADP-isocitrate dehydrogenase is required for Arabidopsis stomatal movement

“…Interestingly, peroxisomes also contain a battery of enzymes capable of detoxifying H 2 O 2 , catalase, and ascorbate peroxidase (APX) (Bunkelmann and Trelease 1996), an enzymatic component of the ascorbate-glutathione cycle, which is located in the peroxisomal membrane (Corpas and Trelease 1998). The peroxisomal NADP-ICDH is also essential for the ascorbate-glutathione cycle as it regenerates NADPH used by the GR and MDAR (Leterrier et al 2005;Romero-Puertas et al 2006). In other words, in the picdh-1 and picdh-2 mutants, the absence of a functional peroxisomal NADP-ICDH isozyme could prevent the efficient removal of H 2 O 2 (and consequently the H 2 O 2 -induced NO) by the peroxisomal ascorbate-glutathione cycle, leading to stomatal closure.…”