Catalytic features and crystal structure of a tau class glutathione transferase from Glycine max specifically upregulated in response to soybean mosaic virus infections

Abstract

The plant tau class glutathione transferases (GSTs) play important roles in biotic and abiotic stress tolerance in crops and weeds. In this study, we systematically examined the catalytic and structural features of a GST isoenzyme from Glycine max (GmGSTU10-10). GmGSTU10-10 is a unique isoenzyme in soybean that is specifically expressed in response to biotic stress caused by soybean mosaic virus (SMV) infections. GmGSTU10-10 was cloned, expressed in Escherichia coli, purified and characterized. The results showed that GmGSTU10-10 catalyzes several different reactions and exhibits wide substrate specificity. Of particular importance is the finding that the enzyme shows high antioxidant catalytic function and acts as hydroperoxidase. In addition, its Km for GSH is significantly lower, compared to other plant GSTs, suggesting that GmGSTU10-10 is able to perform efficient catalysis under conditions where the concentration of reduced glutathione is low (e.g. oxidative stress). The crystal structure of GmGSTU10-10 was solved by molecular replacement at 1.6Å resolution in complex with glutathione sulfenic acid (GSOH). Structural analysis showed that GmGSTU10-10 shares the same overall fold and domain organization as other plant cytosolic GSTs; however, major variations were identified in helix H9 and the upper part of helix H4 that affect the size of the active site pockets, substrate recognition and the catalytic mechanism. The results of the present study provide new information into GST diversity and give further insights into the complex regulation and enzymatic functions of this plant gene superfamily.

Insights into ligand binding to a glutathione S-transferase from mango: Structure, thermodynamics and kinetics

“…The GSH-glycine residue is more flexible and makes a hydrogen bond with K41. Similar contacts are found in other Tau-GST structures with GSH or GSX bound [49]. It is also remarkable that catalytic S14 is flanked by prolines (P13 and P15) and this feature is also shared with maize Tau-class GST (PDB 1GWC).…”

Glutathione S-Transferase Enzymes in Plant-Pathogen Interactions

“…Furthermore, GSTU10-10 was identified in soybean specifically induced in response to systemic infection by Soybean mosaic virus (SMV). Characterization of the GSTU10-10 isoenzyme revealed that it has an antioxidant catalytic function by acting as a hydroperoxidase and has a very low K m for GSH suggesting that GSTU10-10 is able to perform efficient catalysis under conditions where GSH concentrations are low, e.g., during oxidative stress (Skopelitou et al, 2015). A long term systemic infection of peach by Apple chlorotic leaf spot virus (ACLSV), the causal agent of “viruela” disease was investigated focusing on changes in host oxidative stress parameters and antioxidant capacity (García-Ibarra et al, 2011).…”

Functional, Structural and Biochemical Features of Plant Serinyl-Glutathione Transferases

“…In fact, it is quite well documented in many species that the expression of GSTF and GSTU genes is often induced in response to environmental constraints. This includes heavy-metal exposure (Moons, 2003; Ahsan et al, 2008; Reid et al, 2013; Tripathi et al, 2014), salinity, heat, cold, drought (Jha et al, 2011; Tiwari et al, 2016; Yang et al, 2016; Xu et al, 2018; Srivastava et al, 2019), or biotic interactions such as pathogenic interaction (Rinaldi et al, 2007; Skopelitou et al, 2015; Kao et al, 2016). The expression of several GSTF and GSTU genes is also enhanced in response to phytohormones including abscisic acid, auxin, ethylene, methyl jasmonate and salicylic acid, to herbicides and to herbicide safeners, and more generally to treatments leading to an oxidative stress (DeRidder, 2002; Wagner et al, 2002; Lieberherr et al, 2003; Smith et al, 2003, 2004; Sappl et al, 2004, 2009; Chen et al, 2012; Chronopoulou et al, 2017b).…”