The role of GST omega in metabolism and detoxification of arsenic in clam Ruditapes philippinarum.
The major hazard of arsenic in living organisms is increasingly being recognized. Marine mollusks are apt to accumulate high levels of arsenic, but knowledge related to arsenic detoxification in marine mollusks is still less than sufficient. In this study, arsenic bioaccumulation as well as the role of glutathione S-transferase omega (GSTΩ) in the process of detoxification were investigated in the Ruditapes philippinarum clam after waterborne exposure to As(III) or As(V) for 30 days. The results showed that the gills accumulated significantly higher arsenic levels than the digestive glands. Arsenobetaine (AsB) and dimethylarsenate (DMA) accounted for most of the arsenic found, and monomethylarsonate (MMA) can be quickly metabolized. A subcellular distribution analysis showed that most arsenic was in biologically detoxified metal fractions (including metal-rich granules and metallothionein-like proteins), indicating their important roles in protecting cells from arsenic toxicity. The relative mRNA expressions of two genes encoding GSTΩ were up-regulated after arsenic exposure, and the transcriptional responses were more sensitive to As(III) than As(V). The recombinant GSTΩs exhibited high activities at optimal conditions, especially at 37 °C and pH 4-5, with an As(V) concentration of 60 mM. Furthermore, the genes encoding GSTΩ significantly enhance the arsenite tolerance but not the arsenate tolerance of E. coli AW3110 (DE3) (ΔarsRBC). It can be deduced from these results that GSTΩs play an important role in arsenic detoxification in R. philippinarum.
['Chen|Lizhu|L|', 'Wu|Huifeng|H|', 'Zhao|Jianmin|J|', 'Zhang|Wei|W|', 'Zhang|Li|L|', 'Sun|Shan|S|', 'Yang|Dinglong|D|', 'Cheng|Bo|B|', 'Wang|Qing|Q|']
D000818:Animals D053502:Arsenate Reductases D001149:Arsenates D001151:Arsenic D049872:Bivalvia D004926:Escherichia coli D015971:Gene Expression Regulation, Enzymologic D005982:Glutathione Transferase D006863:Hydrogen-Ion Concentration D008658:Inactivation, Metabolic D010641:Phenotype D012333:RNA, Messenger D011994:Recombinant Proteins D020539:Sequence Analysis, Protein D013347:Subcellular Fractions D013379:Substrate Specificity D013696:Temperature D014018:Tissue Distribution D014874:Water Pollutants, Chemical
Metabolism Arsenic Bioaccumulation Glutathione S-transferase omega Subcellular distribution