Proteomic identification of an alpha class glutathione S-transferase in freshwater snails (Bulinus globosus): supplementary material

Abstract

Bulinus globosus is a freshwater snail that serves as intermediate host for Schistosoma haematobium and is known to be drought-tolerant. A previous report on the alteration in the status of glutathione S-transferase (GST) in B. globosus during aestivation and recovery, suggested that GST might be involved in the adaptation of the organism to drought. Therefore, the present study aims to characterize GST isoforms that are displayed in snails under drought stress, sampled during the dry season, and those under recovery, sampled during the rainy season. Our data show that the hepatopancreas contained the highest level of GST compared to foot muscle, hemolymph, and visceral mass. GST activity in the hepatopancreas of snails under drought stress was about 2–3 times higher than that of the recovered snails. Activity staining of a polyacrylamide gel revealed that B. globosus both in the active and inactive state has at least three forms of GST. Based on SDS-PAGE, the multiplicity of the main GSTs in the hepatopancreas of B. globosus (BgGSTs) was further revealed by the presence of five protein bands. In addition, LC-MS/MS analysis of BgGST 2, 3 and 4 revealed the expression of alpha GST. In conclusion, B. globosus exhibits tissue-specific expression of multiple GSTs with elevated activities when the organism is under stress. Elevated activities coupled with an alpha GST class expression accentuate the role of BgGSTs as an antioxidant defense system, in particular under stress conditions.