Functional & structural studies of Stonustoxin (SNTX), a lethal factor from Stonefish (Synanceja Horrida) venom

Abstract

Stonustoxin (SNTX) is a 148kDa, dimeric, multifunctional protein isolated from stonefish Synanceja horrida. SNTX (10-640ng/ml) progressively causes vasorelaxation to endothelium-intact, PE-precontracted rat thoracic aortic rings. The vasorelaxation was inhibited by L-NAME, PAG and BCA. Use of L-NAME with PAG or BCA showed that H2S works synergistically with NO to bring about SNTX-induced vasorelaxation. This is the first report on the involvement of H2S working together with NO to mediate a toxina??s biological effect. Interestingly, an unexpected transient increase in tone of resting rat thoracic aortic rings was observed with L-cysteine. SNTX possesses a novel B30.2 domain in each subunit. Expression and purification of Glutathione-S-transferase-B30.2 fusion proteins from E. coli BL21 resulted in co-expression of chaperonin GroEL and aggregation of fusion proteins into inclusion bodies. The proteins were not active in vasorelaxation and further studies need to be conducted.