Glutathione Is a Key Player in Metal-Induced Oxidative Stress Defenses

Abstract

Abstract:Since the industrial revolution, the production, and consequently the emission of metals, has increased exponentially, overwhelming the natural cycles of metals in many ecosystems. Metals display a diverse array of physico-chemical properties such as essential versus non-essential and redox-active versus non-redox-active. In general, all metals can lead to toxicity and oxidative stress when taken up in excessive amounts, imposing a serious threat to the environment and human health. In order to cope with different kinds of metals, plants possess defense strategies in which glutathione (GSH; γ-glu-cys-gly) plays a central role as chelating agent, antioxidant and signaling component. Therefore, this review highlights the role of GSH in: (1) metal homeostasis; (2) antioxidative defense; and (3) signal transduction under metal stress. The diverse functions of GSH originate from the sulfhydryl group in cysteine, enabling GSH to chelate metals and participate in redox cycling.

Evaluation of Thiol Raman Activities and pKa Values Using Internally Referenced Raman-Based pH Titration

“…[8][9][10][11][12][13] Biological thiols like glutathione and cysteine have multiple functions in vital biological processes in humans, animals and plants. [14][15][16][17] One key indicator of thiol reactivity is its pKa value. Generally, there are several methods available for pKa determination.…”

Glutathione in plants: biosynthesis and physiological role in environmental stress tolerance

“…The activation of the PCS enzyme by the metal itself mainly regulates the PC formation. Phytochelatins are reported to chelate Cd most effectively, followed by As (Jozefczak et al 2012); the other preference order for chelation of metals are (Pasternak et al 2008). The vacuole contains the sequestered PC-ion complexes, thereby reducing toxic metal effects.…”

“…The high affinity for metals imparted by the GSH thiol (-SH) group, coupled with the fact that GSH is a precursor of PCs. It is the reason why GSH is considered to be a very important biomolecule in the process of scavenging metals (Jozefczak et al 2012). Enzymatic oligomerization of GSH results in phytochelatins formation to give a generalized structure of (c-Glu-Cys) n -Gly (n = 2-11).…”

Defects in a New Class of Sulfate/Anion Transporter Link Sulfur Acclimation Responses to Intracellular Glutathione Levels and Cell Cycle Control

“…A plausible transport function for SMT15 might be in maintaining metal ion homeostasis through its function as a cotransporter (Lee et al, 2014;Srinivasan et al, 2014). Glutathione binds to and helps detoxify heavy metals and typically accumulates in response to elevated metals (Cobbett and Goldsbrough, 2002;Jozefczak et al, 2012;Zagorchev et al, 2013), so its elevated levels in smt15-1 could reflect a response to altered metal ion levels. An alternative possibility is that SMT15 is not a transporter but a sensor/signaling protein linked to sulfur metabolism, glutathione metabolism, and/or metal stress.…”