Functional site of bukatoxin, an alpha-type sodium channel neurotoxin from the Chinese scorpion (Buthus martensi Karsch) venom: probable role of the (52)PDKVP(56) loop.
Alpha-toxins from scorpion venoms prolong the action potential of excitable cells by blocking sodium channel inactivation. We have purified bukatoxin, an alpha-toxin from scorpion (Buthus martensi Karsch) venom, to homogeneity. Bukatoxin produced marked relaxant responses in the carbachol-precontracted rat anococcygeus muscle (ACM), which were mediated through the L-arginine-nitric oxide synthase-nitric oxide pathway, consequent to a neuronal release of nitric oxide. Based on the presence of proline residues in the flanking segments of protein-protein interaction sites, we predicted the site between (52)PP(56) to be the potential interaction site of bukatoxin. A homology model of bukatoxin indicated the presence of this site on the surface. Buka11, a synthetic peptide designed based on this predicted site, produced a concentration-dependent nitric oxide-mediated relaxant response in ACM. Using alanine-substituted peptides, we have shown the importance (53)DKV(55) flanked by proline residues in the functional site of bukatoxin.
Srinivasan
K N
KN
Nirthanan
S
S
Sasaki
T
T
Sato
K
K
Cheng
B
B
Gwee
M C
MC
Kini
R M
RM
Gopalakrishnakone
P
P
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002217:Carbachol / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D019476:Insect Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009126:Muscle Relaxation / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009498:Neurotoxins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D009599:Nitroprusside / Q000494:pharmacology; D010455:Peptides / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D011487:Protein Conformation; D051381:Rats; D012604:Scorpion Venoms / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism* / Q000494:pharmacology; D016415:Sequence Alignment; D015222:Sodium Channels / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D014269:Trifluoroacetic Acid / Q000494:pharmacology
D019476:Insect Proteins; D009498:Neurotoxins; D010455:Peptides; D012604:Scorpion Venoms; D015222:Sodium Channels; C425773:bukatoxin; D009599:Nitroprusside; D009569:Nitric Oxide; D013779:Tetrodotoxin; D002217:Carbachol; D014269:Trifluoroacetic Acid; D019331:NG-Nitroarginine Methyl Ester