Scavenging of Hydrogen Peroxide in Prokaryotic and Eukaryotic Algae: Acquisition of Ascorbate Peroxidase during the Evolution of Cyanobacteria

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Ascorbate (AsA) peroxidase was found in six species of cyanobacteria among ten species tested. Upon the addition of H_2^<18>O_2 to the cells of AsA peroxidase-containing cyanobacteria, <16>^O_2 derived from water and <18>^O_2 derived from H_2<18>^O_2 Were evolved in the light. The evolution of <16>^O_2 was inhibited by DCMU and did not occur in the dark, but <18>^O_2 was evolved even in the dark or in the presence of DCMU. Similar light-dependent evolution of <16>^O_2 Was observed in the cells of AsA peroxidase-containing Euglena and Chlamydomonas. However, the cells of AsA peroxidase-lacking cyanobacteria evolved only <18>^O_2 in either the light or dark. Furthermore, the quenching of chlorophyll fluorescence induced by hydrogen peroxide was observed only in the cells of the AsA peroxidase-containing Synechocystis 6803, and not in the cells of Anacystis nidulans which lacks AsA peroxidase. Thus, cyanobacteria can be divided into two groups, those that has and those that lacks AsA peroxidase. The first group scavenges hydrogen peroxide with the peroxidase using a photoreductant as the electron donor, and the second group only scavenges hydrogen peroxide with catalase.
日本植物生理学会の論文