Membrane-damaging activity with A chain and B chain of beta-bungarotoxin.
Beta-bungarotoxin (beta-Bgt) consists of A chain (a phospholipase A2 subunit) and B chain, cross-linked by an intersubunit disulfide bridge. In contrast to a marginal activity noted with beta-Bgt, recombinant A1 chain and B1 chain markedly induced release of calcein from phospholipid vesicles. Reduction of intersubunit disulfide bond by dithiothreitol or glutathione enhanced membrane-damaging activity of beta-Bgt. Moreover, phospholipid-binding capability of recombinant A1 and B1 chains was higher than that of beta-Bgt. In contrast to beta-Bgt, A1 and B1 chains preferably bound lipids with a preference for anionic over zwitterionic phospholipids. Removal of positively charged residues lying on the interface between A chain and B chain resulted in abolishment of membrane-permeabilizing activity of B chain. Taken together, our data indicate that both A and B chains possess the capability to induce vesicle leakage, and reduction of interchain disulfide bond markedly releases this ability from intact beta-Bgt molecule.
Liu
Wen-Hsin
WH
Institute of Biomedical Sciences, National Sun Yat-Sen University-Kaohsiung Medical University Joint Research Center, National Sun Yat-Sen University, No. 70 Lien-Hai Road, Kaohsiung 804, Taiwan.
Kao
Pei-Hsiu
PH
Lin
Shinne-Ren
SR
Chang
Long-Sen
LS
D000818:Animals; D002038:Bungarotoxins / Q000737:chemistry* / Q000633:toxicity*; D017838:Bungarus / Q000502:physiology; D004546:Elapid Venoms / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D054467:Phospholipases A2 / Q000378:metabolism; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D021122:Protein Subunits / Q000737:chemistry* / Q000633:toxicity*
D002038:Bungarotoxins; D004546:Elapid Venoms; D008081:Liposomes; D010743:Phospholipids; D021122:Protein Subunits; D054467:Phospholipases A2