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Improved metal phytoremediation through plant biotechnology
Published in A.A. Balkema, Tailings and Mine Waste 2000, 2022
E.A.H. Pilon-Smits, Y.-L. Zhu, N. Terry
The goal of this study is to enhance heavy metal tolerance and accumulation in Indian mustard by means of genetic engineering. To this aim, Indian mustard plants were engineered to overproduce the heavy metal binding peptides glutathione and phytochelatins. Glutathione (γ-Glu-Cys-Gly, GSH) plays several important roles in the defense of plants against environmental stresses, and is the precursor for phytochelatins (PCs): heavy metal-binding peptides involved in heavy metal tolerance and sequestration. Glutathione is synthesized from its constituent amino acids in two enzymatic reactions, catalyzed by γ-glutamyl-cysteine synthetase (γ-ECS) and glutathione synthetase (GS), respectively (Fig. 1). Upon exposure to heavy metals, glutathione is aggregated to phytochelatins (structure: (γ-glu-cys)ngly), by phytochelatin synthase (PS).
Saccharomyces cerevisiae
Published in Yoshikatsu Murooka, Tadayuki Imanaka, Recombinant Microbes for Industrial and Agricultural Applications, 2020
Glutathione is synthesized by consecutive reactions catalyzed by γ-l-glutamyl-l-cysteine synthetase (GSH A) and glutathione synthetase (GSH B) from L-glutamate, L-cysteine, and glycine, in the presence of ATP (Scheme 1). For a further improvement of the glutathione productivity of the bioreactor system, the glutathione synthetic process in E. coli B was enzymati-cally and genetically analyzed. This section deals with the properties of two synthetases (GSH A and GSH B) and their genes (gsh A and gsh B).
Roles of phytohormones in mitigating abiotic stress in plants induced by metal(loid)s As, Cd, Cr, Hg, and Pb
Published in Critical Reviews in Environmental Science and Technology, 2023
Zhi-Hua Dai, Dong-Xing Guan, Jochen Bundschuh, Lena Q. Ma
Besides cell walls, glutathione is important in protecting plants against Cd-induced oxidative stress, which is a component of phytochelatin involved in Cd chelation (Figure 1; Szalai et al., 2009). Salicylic acid (SA) is linked to glutathione biosynthesis. For example, the glutathione content is lower in Cd-stressed leaves in SA-mutant than in wild-type in A. thaliana (Guo et al., 2016). Furthermore, SA application increases its glutathione content in peppermint under Cd stress (Table 1; Ahmad et al., 2018). The SA-induced glutathione increase under Cd stress can be explained by (1) increased transcription in serine acetyltransferase, the precursor gene to catalyze cysteine formation (Freeman et al., 2005), (2) enhanced S uptake, a key element for GSH synthesis (Guo et al., 2016), and (3) increased activities of glutathione synthetase and glutathione reductase to maintain GSH in the reduced state (Guo et al., 2016). To further alleviate Cd stress, plants can sequester PC-Cd complexes into the vacuoles through ATP-binding cassette (ABC) transporters (Bovet et al., 2005). An ABC transporter from soybean is identified under salicylic acid induction (Eichhorn et al., 2006). However, whether ABC transporters are involved in SA-induced Cd tolerance needs further study.
Involvement of glutathione and glutathione metabolizing enzymes in Pistia stratiotes tolerance to arsenite
Published in International Journal of Phytoremediation, 2020
Fernanda Vidal de Campos, Juraci Alves de Oliveira, Adinan Alves da Silva, Cleberson Ribeiro, Sebastián Giraldo Montoya, Fernanda dos Santos Farnese
The increase in glutathione concentration is one of the first responses of plants to As and is associated with greater tolerance to the metalloid (Hernández et al.2015; Dixit et al.2016). The first enzyme involved in glutathione synthesis is γ-glutamyl-cysteine synthetase (glutamate-cysteine ligase (EC 6.3.2.2)), which catalyzes the peptide bond between the γ-carboxyl group of glutamate and the amine group of cysteine, forming the dipeptide L-γ-glutamyl-L- cysteine. For the formation of this peptide bond, the γ-carboxyl group is activated by ATP. The second reaction is catalyzed by glutathione synthetase (GSH-S). In this reaction ATP activates the carboxyl group of cysteine to enable it to be linked to the amine group of glycine, forming the tripeptide L-γ-glutamyl-L-cysteinylglycine (Hasanuzzaman et al.2017).
Buthionine sulfoximine and chemoresistance in cancer treatments: a systematic review with meta-analysis of preclinical studies
Published in Journal of Toxicology and Environmental Health, Part B, 2023
Camila dos Reis Oliveira, Joedna Cavalcante Pereira, Andressa Barros Ibiapina, Italo Rossi Roseno Martins, João Marcelo de Castro e Sousa, Paulo Michel Pinheiro Ferreira, Felipe Cavalcanti Carneiro da Silva
The first stage in GSH synthesis consists of an interaction between cysteine and glutamate, whose reaction is catalyzed by γ-glutamylcysteine synthetase (γGCS) leading to γ-glutamylcysteine formation, which is a critical phase for GSH generation and functions as an active site of oxidizing agents, such as buthionine sulfoximine (BSO). Subsequently, a reaction through glutathione synthetase (GSS) adds glycine to the structure and terminates in GSH biosynthesis (Asantewaa and Harris 2021; Meister 1991).