ABSTRACT
Maitotoxin (MTX) is a ladder-shaped polyether produced by the epiphytic dinoflagellate Gambierdiscus toxicus. It is known to elicit potent toxicity against mammals and induce influx of Ca(2+) into cells. An artificial ladder-shaped polyether possessing a 6/7/6/6/7/6/6 heptacyclic ring system, which was designed for elucidating interactions with transmembrane proteins, was found to be the most potent inhibitor against MTX-induced Ca(2+) influx that has ever been reported.
Subject(s)
Calcium/metabolism , Ethers, Cyclic/chemistry , Marine Toxins/toxicity , Oxocins/toxicity , Animals , Dinoflagellida/chemistry , Ethers, Cyclic/pharmacology , Glioma/metabolism , Hydrophobic and Hydrophilic Interactions , Ion Transport/drug effects , Marine Toxins/chemistry , Marine Toxins/isolation & purification , Membrane Proteins/metabolism , Oxocins/chemistry , Oxocins/isolation & purification , Rats , Tumor Cells, CulturedABSTRACT
As is the case with other ladder-shaped polyether compounds, yessotoxin is produced by marine dinoflagellate, and possesses various biological activities beside potent toxicity. To gain a better understanding of the molecular mechanism for high affinity between these polyethers and their binding proteins, which accounts for their powerful biological activities, we searched for its binding proteins from human blood cells by using the biotin-conjugate of desulfated YTX as a ligand. By a protein pull-down protocol with use of streptavidin beads, a band of specifically binding proteins was detected in SDS-PAGE. HPLC-tandem mass spectrometry (MS/MS) indicated that Rap 1A, one of Ras superfamily proteins, binds to the YTX-linked resins. Western blotting and surface plasmon resonance experiments further confirmed that Rap1A specifically binds to YTX with the K(D) value around 4 µM.
