Chloroplastic ascorbate peroxidases targeted to stroma or thylakoid membrane: The chicken or egg dilemma

Abstract

Ascorbate peroxidases (APXs) are heme peroxidases that remove hydrogen peroxide in different subcellular compartments with concomitant ascorbate cycling. Here, we analysed and discussed phylogenetic and molecular features of the APX family. Ancient APX originated as a soluble stromal enzyme, and early during plant evolution, acquired both chloroplast‐targeting and mitochondrion‐targeting sequences and an alternative splicing mechanism whereby it could be expressed as a soluble or thylakoid membrane‐bound enzyme. Later, independent duplication and neofunctionalization events in some angiosperm groups resulted in individual genes encoding stromal, thylakoidal and mitochondrial isoforms. These data reaffirm the complexity of plant antioxidant defenses that allow diverse plant species to acquire new means to adapt to changing environmental conditions.

Boron Reduced Copper Excess-Induced Oxidative Damage in Citrus sinensis by Modulating Reactive Oxygen Species and Methylglyoxal Formation and Their Detoxification Systems

“…DHAR can reduce DHA back to ASC by using two GSH molecules, while producing a GSSG molecule. Using NAD(P)H as the substrate, GR can convert GSSG back to GSH [ 44 ]. ASC and GSH are the two most prevalent soluble antioxidants in plant cells [ 43 ].…”

Cold priming on pathogen susceptibility in the Arabidopsis eds1 mutant background requires a functional stromal Ascorbate Peroxidase

“… 32 , 33 The interplay of tAPX and sAPX provides two spatial layers for scavenging photosynthesis-related H 2 O 2 in the plastid. 27 , 28 In this context, sAPX and tAPX have mainly redundant functions for photooxidative protection under abiotic stress situations in mature plants. 34–36 However, also distinct roles are reported.…”

Cold exposure transiently increases resistance ofArabidopsis thalianaagainst the fungal pathogenBotrytis cinerea

“…Tightly functionally interacting with superoxide dismutases, chloroplast ascorbate peroxidases (APX) utilize ascorbate as an electron donor to detoxify H 2 O 2 (Groden and Beck, 1978). Thylakoid-bound APX (tAPX) is part of a first layer of protection and scavenges photosynthesis-related H 2 O 2 directly at the thylakoid membrane (Asada, 1999; Jardim-Messeder et al, 2022). Stromal APX (sAPX) provides downstream antioxidant protection in the plastid stroma (Asada, 1999; Jardim-Messeder et al, 2022).…”