Identification and Comparative Analysis of H2O2-Scavenging Enzymes (Ascorbate Peroxidase and Glutathione Peroxidase) in Selected Plants Employing Bioinformatics Approaches.

Ibrahim I Ozyigit,Ertugrul Filiz,Kuaybe Y Kurtoglu,Naser A Anjum,Münir X Öztürk,Münir X Öztürk,Recep Vatansever,Ibrahim Koc

doi:10.3389/fpls.2016.00301

Abstract

Among major reactive oxygen species (ROS), hydrogen peroxide (H2O2) exhibits dual roles in plant metabolism. Low levels of H2O2 modulate many biological/physiological processes in plants; whereas, its high level can cause damage to cell structures, having severe consequences. Thus, steady-state level of cellular H2O2 must be tightly regulated. Glutathione peroxidases (GPX) and ascorbate peroxidase (APX) are two major ROS-scavenging enzymes which catalyze the reduction of H2O2 in order to prevent potential H2O2-derived cellular damage. Employing bioinformatics approaches, this study presents a comparative evaluation of both GPX and APX in 18 different plant species, and provides valuable insights into the nature and complex regulation of these enzymes. Herein, (a) potential GPX and APX genes/proteins from 18 different plant species were identified, (b) their exon/intron organization were analyzed, (c) detailed information about their physicochemical properties were provided, (d) conserved motif signatures of GPX and APX were identified, (e) their phylogenetic trees and 3D models were constructed, (f) protein-protein interaction networks were generated, and finally (g) GPX and APX gene expression profiles were analyzed. Study outcomes enlightened GPX and APX as major H2O2-scavenging enzymes at their structural and functional levels, which could be used in future studies in the current direction.

Highlights

Reactive oxygen species (ROS), once perceived as toxic byproducts, were known to cause oxidative damage in cells (Mittler et al, 2004; Suzuki and Mittler, 2006)
H2O2 has been accepted as a central component of signal transduction pathways in plant-adaptation to altered environmental conditions as it is both the only ROS with high permeability across membranes and its high stability when compared to other ROS with ∼1 ms half-life (Bienert et al, 2007; Dynowski et al, 2008; Petrov and Van Breusegem, 2012)
glutathione peroxidase (GPX) and ascorbate peroxidase (APX) are two major ROS-scavenging enzymes which catalyze the reduction of H2O2 to prevent H2O2-derived cellular damage

Summary

Introduction

Reactive oxygen species (ROS), once perceived as toxic byproducts, were known to cause oxidative damage in cells (Mittler et al, 2004; Suzuki and Mittler, 2006). Novel regulatory roles of these species were revealed in a wide range of biological processes such as cell signaling, growth, development, programmed cell death, and plant responses to various biotic/abiotic stress factors (Mullineaux and Karpinski, 2002; Uzilday et al, 2014). H2O2 is an endogenous ROS species known to play a dual role in plants, where it is beneficial at low concentrations but lethal at higher levels (Petrov and Van Breusegem, 2012). H2O2 has been accepted as a central component of signal transduction pathways in plant-adaptation to altered environmental conditions as it is both the only ROS with high permeability across membranes (that enables the transport of signals to distant sites) and its high stability when compared to other ROS with ∼1 ms half-life (Bienert et al, 2007; Dynowski et al, 2008; Petrov and Van Breusegem, 2012). APX may have pivotal roles in ROSscavenging because even very low concentrations are sufficient for H2O2 decomposition (Anjum et al, 2014; Sofo et al, 2015)

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Conclusion