Association–Dissociation of Glycolate Oxidase with Catalase in Rice: A Potential Switch to Modulate Intracellular H 2 O 2 Levels

Abstract

Rapid and dynamic change in hydrogen peroxide (H2O2) levels can serve as an important signal to regulate various biological processes in plants. The change is realized by tilting the balance between its production and scavenging rates, in which membrane-associated NADPH oxidases are known to play a crucial role. Functioning independently from NADPH oxidases, glycolate oxidase (GLO) was recently demonstrated as an alternative source for H2O2 production during both gene-for-gene and non-host resistance in plants. In this study, we show that GLO physically interacts with catalase (CAT) in rice leaves, and that the interaction can be deregulated by salicylic acid (SA). Furthermore, the GLO-mediated H2O2 accumulation is synergistically enhanced by SA. Based on the well-known mechanism of substrate channeling in enzyme complexes, SA-induced H2O2 accumulation likely results from SA-induced GLO-CAT dissociation. In the GLO-CAT complex, GLO-mediated H2O2 production during photorespiration is very high, whereas the affinity of CAT for H2O2 (measured Km ≈ 43 mM) is extraordinarily low. This unique combination can further potentiate the increase in H2O2 when GLO is dissociated from CAT. Taken together, we propose that the physical association-dissociation of GLO and CAT, in response to environmental stress or stimuli, seems to serve as a specific mechanism to modulate H2O2 levels in rice.

Silenced rice in both cytosolic ascorbate peroxidases displays pre-acclimation to cope with oxidative stress induced by 3-aminotriazole-inhibited catalase

“…GO activity, the most important enzymes involved in the production of H 2 O 2 in peroxisomes (Corpas, 2015) suffered strong down-regulation in APX1/2 plants, evidencing a strong synchrony between CAT and GO (Zhang et al, 2016). Recently we have reported that CAT inhibition by 3-AT in rice leaves induce reduction in GO activity, especially in peroxisomal APX4 knockdown mutants and these changes were related to lower H 2 O 2 accumulation (Sousa et al, 2015).…”

A Quantitative Proteomic Analysis of Brassinosteroid-induced Protein Phosphorylation in Rice (Oryza sativa L.)

“…CATs are also targets of excess copper toxicity, which leads to retarded seed germination in rice (Ye et al, 2014). A very recent study suggested that the physical association-dissociation of GLO (Glycolate Oxidase; H 2 O 2 producer) and CAT serve as a specific machinery to modulate H 2 O 2 levels in rice (Zhang et al, 2016). Moreover, a potential PEX5-CATA-SOD interaction relationship was suggested by our PPI analysis ( Figure 4C ).…”

Engineering a New Chloroplastic Photorespiratory Bypass to Increase Photosynthetic Efficiency and Productivity in Rice

“…The oxalate produced is then completely oxidized into CO 2 and H 2 O 2 by OsOXO3, an isoform of oxalate oxidase in rice that has a stable optimum pH ranging from 6.0 to 8.0 (Li et al, 2015). H 2 O 2 produced by the three reactions is scavenged by OsCATC, an isoform of catalase in rice leaves (Zhang et al, 2016). We named this bypass the GOC bypass after the three enzymes (glycolate oxidase, oxalate oxidase, catalase) used.…”