The Roles of Plant Peroxidases in the Metabolism of Reactive Nitrogen Species and Other Nitrogenous Compounds

Abstract

Peroxidases can metabolize nitrogenous compounds with various degrees of oxidation, such as nitrates, nitrites, and reactive nitrogen species (RNS). The roles of peroxidases in the metabolism of nitrogenous compounds in plants are poorly understood. Due to the continuous transformations of one RNS and reactive oxygen species (ROS) into other species, and also versatile nature of peroxidases, the mechanisms of the interplay between these oxidoreductases and nitrogenous compounds are complex and diverse. In this review, we critically assess the current knowledge on the unique roles of plant and fungal peroxidases in the metabolism of nitrogenous compounds. The interactions of nitrogenous compounds with peroxidases are implicated in signaling by producing or binding RNS and thus effecting the activities of components of signal transduction pathways. The interactions of RNS with peroxidases also provide a key mechanism of posttranslational protein modifications as a consequence of the peroxidase-catalyzed nitration of tyrosine and tryptophan derivatives in proteins in the presence of nitrite and hydrogen peroxide. Activities of a large number of proteins and enzymes depend on tyrosine residues. The interactions of RNS and other nitrogenous compounds with peroxidases may lead to the formation of nitrophenols, which exhibit regulatory effects. Peroxidases may metabolize synthetic nitrophenol derivatives and thus provide an essential mechanism for removal of toxic compounds including xenobiotics.