Glutathione

Abstract

Glutathione is a simple sulfur compound composed of three amino acids and the major non-protein thiol in many organisms, including plants. The functions of glutathione are manifold but notably include redox-homeostatic buffering. Glutathione status is modulated by oxidants as well as by nutritional and other factors, and can influence protein structure and activity through changes in thiol-disulfide balance. For these reasons, glutathione is a transducer that integrates environmental information into the cellular network. While the mechanistic details of this function remain to be fully elucidated, accumulating evidence points to important roles for glutathione and glutathione-dependent proteins in phytohormone signaling and in defense against biotic stress. Work in Arabidopsis is beginning to identify the processes that govern glutathione status and that link it to signaling pathways. As well as providing an overview of the components that regulate glutathione homeostasis (synthesis, degradation, transport, and redox turnover), the present discussion considers the roles of this metabolite in physiological processes such as light signaling, cell death, and defense against microbial pathogen and herbivores.

Glutathione – linking cell proliferation to oxidative stress

“…For example, a change in cytosolic redox potential of about 50 mV is sufficient to 20 significantly alter the balance between oxidized and reduced forms of TRX-regulated proteins (97). As discussed previously (1), an increase in redox potential from -350 to -300 mV converts the TRX-regulated chloroplast glucose-6-phosphate dehydrogenase 1 from almost completely inactive to active (98).Small changes in cellular NADP:NADPH ratiosmay be sufficient to allow significant changes in the glutathione redox potential, and hence facilitate signal amplification in vivo. Given the low K M of GR for NADPH (99, 100) compared to likely cytosolic NADPH concentrations (around 150 µM; 101), this could occur through adjustment of relative concentrations in the NADP-glutathione equilibrium rather than kinetic limitation of GR activity by NADPH.…”

“…However, accumulating evidence demonstrates that GSH is required for the operation of a diverse range of processes that include growth, stress tolerance and cell suicide programs (1,2). Within this context, the requirement for GSH is undoubtedly linked to signalling function, particularly interactions with nitric oxide (NO) and participation in thiol-dependent post-translational protein modifications, which modulate activities, sub-cellular localization, stability or their interactions with partner proteins in plants and animals.…”

“…It is rather surprising therefore that the nuclear GSH pool is much more resistant to depletion than the cytosolic pool, a property that is particularly important during cell proliferation (5)(6)(7)(8). Although relatively little is known about the nuclear thioredoxins (TRX) and glutaredoxins (GRXs) or their functions in plants (9) it is probable that these redox proteins participate in the plethora of thiol-dependent redox regulation mechanisms and post-translational modifications that are required for plant growth and development, particularly through functions in the nuclei.The many important roles of glutathione in plants have been well documented in recent reviews (1,2,10) and hence the following discussion will focus on how GSH functions as a regulator of plant development, with a particular focus on the nuclear GSH and the regulation of mitosis.…”

From Endoplasmic Reticulum to Mitochondria: Absence of the Arabidopsis ATP Antiporter Endoplasmic Reticulum Adenylate Transporter1 Perturbs Photorespiration

“…GSH is a prevalent reducing equivalent in the cell and represents a further factor controlling cellular ROS state (Noctor et al, 2011). Wild-type plants exposed to high CO 2 contained GSH concentrations of 201 nmol g 21 FW, and identically treated mutant lines showed slightly higher GSH levels (283 nmol g 21 FW in er-ant1-1 and 260 nmol g 21 FW in er-ant1-2; Figure 5D).…”

Role of Antioxidant System Components in Adaptation of Elytrigia Repens (L.) ‘Nevski’ to Cadmium

“…Поэтому под-держание высокого уровня GSH, а также опти-мального соотношения его восстановленной и окисленной (GSSG) форм необходимо для нормального метаболизма клетки [Vanacker et al, 2000;Szalai et al, 2009]. В присутствии кадмия опасность изменения соотношения GSH/GSSG особенно высока из-за расходо-вания молекул GSH на синтез фитохелатинов, что может приводить к целому ряду негативных последствий, связанных с изменением окис-лительно-восстановительного баланса клетки [Zhu et al, 1999;Cobbett, Goldsbrough, 2002;Pietrini et al, 2003;Noctor et al, 2011]. В нашем исследовании содержание GSH у растений E. repens в присутствии кадмия сохранялось на уровне контрольного варианта (рис.…”