Activity of Cytosolic Ascorbate Peroxidase (APX) from Panicum virgatum against Ascorbate and Phenylpropanoids

• Published in: International journal of molecular sciences Vol. 24; no. 2; p. 1778
• Main Authors: Zhang, Bixia, Lewis, Jacob A, Kovacs, Frank, Sattler, Scott E, Sarath, Gautam, Kang, ChulHee
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 16.01.2023; MDPI
• Subjects: Alcohol; ascorbate; ascorbate peroxidase; Ascorbate Peroxidases - metabolism; Ascorbic acid; Ascorbic Acid - metabolism; Biodiesel fuels; Biofuels; Biomass; Catalysis; Cell walls; Cellular structure; Crystal lattices; Enzyme kinetics; Genomes; Heme; Hydrogen peroxide; Hydrogen Peroxide - metabolism; L-Ascorbate peroxidase; Lignin; Molecular docking; Molecular Docking Simulation; Mutation; Oxidation; Oxidative stress; Panicum - metabolism; Panicum virgatum; Peroxidase; Phenylpropanoids; Physiology; Plants - metabolism; ROS; Scavenging; stress; Substrates; switchgrass; X-ray crystallography; lignification; stress; ascorbate peroxidase; ROS; ascorbate; oxidation; switchgrass; phenylpropanoids
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms24021778

APX is a key antioxidant enzyme in higher plants, scavenging H O with ascorbate in several cellular compartments. Here, we report the crystal structures of cytosolic ascorbate peroxidase from switchgrass ( L., ), a strategic feedstock plant with several end uses. The overall structure of PviAPX was similar to the structures of other APX family members, with a bound ascorbate molecule at the ɣ-heme edge pocket as in other APXs. Our results indicated that the H O -dependent oxidation of ascorbate displayed positive cooperativity. Significantly, our study suggested that PviAPX can oxidize a broad range of phenylpropanoids with δ-meso site in a rather similar efficiency, which reflects its role in the fortification of cell walls in response to insect feeding. Based on detailed structural and kinetic analyses and molecular docking, as well as that of closely related APX enzymes, the critical residues in each substrate-binding site of PviAPX are proposed. Taken together, these observations shed new light on the function and catalysis of PviAPX, and potentially benefit efforts improve plant health and biomass quality in bioenergy and forage crops.