Mapping the structural determinants of presynaptic neurotoxicity of snake venom phospholipases A2.
Toxicon
; 51(8): 1520-9, 2008 Jun 15.
Article
em En
| MEDLINE
| ID: mdl-18513779
ABSTRACT
The structural features of presynaptically neurotoxic secretory phospholipases A(2) (sPLA(2)s) that are responsible for their potent and specific action are still a matter of debate. To identify the residues that distinguish a highly neurotoxic sPLA(2), ammodytoxin A (AtxA), from a structurally similar but more than two orders of magnitude less toxic Russell's viper sPLA(2), VIIIa, we prepared a range of mutants and compared their properties. The results show that the structural features that confer high neurotoxicity to AtxA extend from its C-terminal part, with a central role of the residues Y115, I116, R118, N119 (the YIRN cluster) and F124, across the interfacial binding surface (IBS) in the vicinity of F24, to the N-terminal helix whose residues M7 and G11 are located on the edges of the IBS. Competition binding studies indicate that the surface of interaction with the neuronal M-type sPLA(2) receptor R180 extends over a similar region of the molecule. In addition, the YIRN cluster of AtxA is crucial for the high-affinity interaction with two intracellular binding proteins, calmodulin and R25. The concept of a single "presynaptic neurotoxic site" on the surface of snake venom sPLA(2)s is not consistent with these results which suggest that different parts of the toxin molecule are involved in distinct steps of presynaptic neurotoxicity.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Venenos de Víboras
/
Fosfolipases A2
/
Neurotoxinas
Limite:
Animals
Idioma:
En
Revista:
Toxicon
Ano de publicação:
2008
Tipo de documento:
Article
País de afiliação:
Eslovênia