Structural highlights
Function
[PA2B1_BUNMU] Snake venom phospholipase A2 (PLA2) that inhibits neuromuscular transmission by blocking acetylcholine release from the nerve termini. PLA2 catalyzes the calcium-dependent hydrolysis of the 2-acyl groups in 3-sn-phosphoglycerides. [VKTH2_BUNMU] Beta-2-bungarotoxin is a presynaptic neurotoxin of the venom. The B chain is homologous to venom basic protease inhibitors but has no protease inhibitor activity and blocks voltage-gated potassium channels (Kv).[1]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
BACKGROUND: beta-bungarotoxin is a heterodimeric neurotoxin consisting of a phospholipase subunit linked by a disulfide bond to a K+ channel binding subunit which is a member of the Kunitz protease inhibitor superfamily. Toxicity, characterized by blockage of neural transmission, is achieved by the lipolytic action of the phospholipase targeted to the presynaptic membrane by the Kunitz module. RESULTS: The crystal structure at 2.45 A resolution suggests that the ion channel binding region of the Kunitz subunit is at the opposite end of the module from the loop typically involved in protease binding. Analysis of the phospholipase subunit reveals a partially occluded substrate-binding surface and reduced hydrophobicity. CONCLUSIONS: Molecular recognition by this Kunitz module appears to diverge considerably from more conventional superfamily members. The ion channel binding region identified here may mimic the regulatory interaction of endogenous neuropeptides. Adaptations of the phospholipase subunit make it uniquely suited to targeting and explain the remarkable ability of the toxin to avoid binding to non-target membranes. Insight into the mechanism of beta-bungarotoxin gained here may lead to the development of therapeutic strategies against not only pathological cells, but also enveloped viruses.
Structure of beta 2-bungarotoxin: potassium channel binding by Kunitz modules and targeted phospholipase action.,Kwong PD, McDonald NQ, Sigler PB, Hendrickson WA Structure. 1995 Oct 15;3(10):1109-19. PMID:8590005[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Wu PF, Wu SN, Chang CC, Chang LS. Cloning and functional expression of B chains of beta-bungarotoxins from Bungarus multicinctus (Taiwan banded krait). Biochem J. 1998 Aug 15;334 ( Pt 1):87-92. PMID:9693106
- ↑ Kwong PD, McDonald NQ, Sigler PB, Hendrickson WA. Structure of beta 2-bungarotoxin: potassium channel binding by Kunitz modules and targeted phospholipase action. Structure. 1995 Oct 15;3(10):1109-19. PMID:8590005
