Membrane-bound conformation and phospholipid components modulate membrane-damaging activity of Taiwan cobra cardiotoxins.
Membrane-damaging activity of Naja naja atra cardiotoxin 3 (CTX3) on 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC)/1,2-dimyristoyl-phosphatidic acid (DMPA) vesicles was approximately 3-fold that of N. naja atra cardiotoxin 4 (CTX4), while CTX3 and CTX4 displayed insignificantly permeabilizing activity in 1,2-dipalmitoyl-phosphatidylcholine (DPPC)/DMPA vesicles. Phospholipid-binding capability and oligomeric assembly upon binding with lipid vesicles did not closely correlate with membrane-damaging potency of CTX3 and CTX4. Geometrical arrangement of CTX3 in contact with POPC/DMPA vesicles was different from that noted with CTX4, and binding forces between CTX3 and POPC/DMPA were stronger than those between CTX4 and POPC/DMPA. Unlike POPC/DMPA, the interaction between CTXs and DPPC/DMPA was drastically reduced by increasing salt concentration. Color transformation of phospholipid/polydiacetylene membrane assay and FTIR spectra analyses revealed that CTX3 and CTX4 adopted different conformationsand modes upon absorption on POPC/DMPA and DPPC/DMPA vesicles. Taken together, our data show that, in addition to membrane packing density and phospholipid-binding capability, membrane-bound conformation of CTXs plays a vital role in displaying membrane-damaging activity.
Kao
Pei-Hsiu
PH
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.
Lin
Shinne-Ren
SR
Wu
Ming-Jung
MJ
Chang
Long-Sen
LS
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D004179:Cobra Cardiotoxin Proteins / Q000737:chemistry / Q000494:pharmacology*; D003124:Colorimetry; D004546:Elapid Venoms / Q000737:chemistry*; D017815:Elapidae; D020404:Glycerophospholipids / Q000737:chemistry; D008081:Liposomes; D008567:Membranes, Artificial; D008969:Molecular Sequence Data; D010539:Permeability / Q000187:drug effects*; D010743:Phospholipids / Q000737:chemistry*; D016415:Sequence Alignment; D013624:Taiwan
D004179:Cobra Cardiotoxin Proteins; D004546:Elapid Venoms; D020404:Glycerophospholipids; D008081:Liposomes; D008567:Membranes, Artificial; D010743:Phospholipids; C082202:cardiotoxin III, Naja naja atra; D015060:1,2-Dipalmitoylphosphatidylcholine; C025602:dimyristoylphosphatidic acid