Characterization of glutathione peroxidase diversity in the symbiotic sea anemone Anemonia viridis

Abstract

Cnidarians living in symbiosis with photosynthetic dinoflagellates (commonly named zooxanthellae) are exposed to high concentrations of reactive oxygen species (ROS) upon illumination. To quench ROS production, both the cnidarian host and zooxanthellae express a full suite of antioxidant enzymes. Studying antioxidative balance is therefore crucial to understanding how symbiotic cnidarians cope with ROS production. We characterized glutathione peroxidases (GPx) in the symbiotic cnidarian Anemonia viridis by analysis of their isoform diversity, their activity distribution in the three cellular compartments (ectoderm, endoderm and zooxanthellae) and their involvement in the response to thermal stress. We identified a GPx repertoire through a phylogenetic analysis showing 7 GPx transcripts belonging to the A. viridis host and 4 GPx transcripts strongly related to Symbiodinium sp. The biochemical approach, used for the first time with a cnidarian species, allowed the identification of GPx activity in the three cellular compartments and in the animal mitochondrial fraction, and revealed a high GPx electrophoretic diversity. The symbiotic lifestyle of zooxanthellae requires more GPx activity and diversity than that of free-living species. Heat stress induced no modification of GPx activities. We highlight a high GPx diversity in A. viridis tissues by genomic and biochemical approaches. GPx activities represent an overall constitutive enzymatic pattern inherent to symbiotic lifestyle adaptation. This work allows the characterization of the GPx family in a symbiotic cnidarian and establishes a foundation for future studies of GPx in symbiotic cnidarians.

Chromophore of an Enhanced Green Fluorescent Protein Can Play a Photoprotective Role Due to Photobleaching

“…While elucidation of the detailed mechanism of this ROS-scavenging action of EGFP is beyond the scope of this study, the data presented herein suggest that similar protective capabilities of the naturally-occurring GFP-like proteins, such as their protective action against visible-or UV-light induced ROS, could be an important contribution to the realm of antioxidant defenses developed by, e.g., symbiotic cnidarians. In particular, it is known that these organisms experience constant pro-oxidative conditions during the daytime [46]. We also draw attention to the fact that the ability of GFP-like proteins to quench ROS should also be taken into account in other areas, where such fluorescent proteins are being implemented as supposedly inert, non-reactive light-excited fluorescent markers, e.g., in fluorescence microscopy or spectroscopic techniques, such as fluorescence correlation spectroscopy.…”

Pharmacological Effects and Toxicogenetic Impacts of Omeprazole: Genomic Instability and Cancer

“…ROS are responsible for modifications in mitochondrial permeability [143], causing mutations and damage to the mitochondrial DNA and the respiratory chain [144,145]. OME can impart cytotoxicity of hyperoxia and induce ROS in lung microvascular endothelial cells, by producing hydrogen peroxide rather than acute hyperoxic lesions (in vitro) [146].…”

Anemonia sulcata and Its Symbiont Symbiodinium as a Source of Anti-Tumor and Anti-Oxidant Compounds for Colon Cancer Therapy: A Preliminary In Vitro Study

“…It is known that cnidarians, including Anemonia sulcata, produce high quantities of antioxidant enzymes (e.g., glutathione peroxidases) to eliminate ROS generated by their symbionts [32]. Moreover, the microalga Symbiodinium produces ROS in normal conditions.…”

“…On the other hand, aqueous extracts of Actinica equina and Anemonia sulcata, which contained the alkaloid homarine, demonstrated antiproliferative activity in the RAW-264.7 cell line (murine macrophage) and human gastric adenocarcinoma cells via the activation of caspase-3 [24]. Besides, Anemonia viridis showed significant antioxidant activity through the presence of glutathione peroxidase and catalase in high concentrations [31,32].…”