Glutathione S-transferase: a versatile protein family

Abstract

Glutathione-S transferase (GST) is a most ancient protein superfamily of multipurpose roles and evolved principally from gene duplication of an ancestral GSH binding protein. They have implemented in diverse plant functions such as detoxification of xenobiotic, secondary metabolism, growth and development, and majorly against biotic and abiotic stresses. The vital structural features of GSTs like highly divergent functional topographies, conserved integrated architecture with separate binding pockets for substrates and ligand, the stringent structural fidelity with high Tm values (50º-60º), and stress-responsive cis-regulatory elements in the promoter region offer this protein as most flexible plant protein for plant breeding approaches, biotechnological applications, etc. This review article summarizes the recent information of GST evolution, and their distribution and structural features with emphasis on the assorted roles of Ser and Cys GSTs with the signature motifs in their active sites, alongside their recent biotechnological application in the area of agriculture, environment, and nanotechnology have been highlighted.

Keywords: cys GST; Active site residues; Detoxification; Evolution; Glutathionylation; Ser.

Fig. 1

Schematic representation of the protein architecture of plant Ser and Cys GSTs. The N-terminal and C-terminal domain are represented in orange containing G and H site, respectively. The position of the active site residue, i.e., Ser and Cys are shown in green and blue circles, respectively, at the G site. Secondary structures are shown as α-helices and β-strands. The stretch of the boxes is directly correlated with the length of the amino acids

Fig. 2

Alignment of Ser-GST sequences of Zeta and Theta class is done, taking the amino acid sequences of A. thaliana, O. sativa, G. max, and V. radiata through Clustal omega alignment tool, and the protein alignments are rendered in ESPript 3.0. Conserved residues are marked with red background in white characters. The catalytic Ser residue is marked with ( ∗). The conserved motifs of Zeta GST [SSCX (W/H) RVIAL] and Theta GSTs (SQPS) are marked with black dashed box (Fig adopted from Vaish et al. 2018)

Fig. 3

Alignment of Cys-GST amino acid sequences of Lambda and DHAR GST classes. The GST amino acid sequences of A. thaliana, O. sativa, G. max, and V. radiata are aligned on Clustal omega alignment tool and the protein alignments are rendered in ESPript 3.0. Conserved residues are marked with red background in white characters. The catalytic Cys residue is marked with ( ∗). The conserved motifs of Lambda GST [CP(F/Y)A] and DHAR GST (CPFC/S) are marked with black dashed box (Fig adopted from Vaish et al. 2018)