New tricks of an old pattern: structural versatility of scorpion toxins with common cysteine spacing.
J Biol Chem
; 287(15): 12321-30, 2012 Apr 06.
Article
em En
| MEDLINE
| ID: mdl-22238341
ABSTRACT
Scorpion venoms are a rich source of K(+) channel-blocking peptides. For the most part, they are structurally related small disulfide-rich proteins containing a conserved pattern of six cysteines that is assumed to dictate their common three-dimensional folding. In the conventional pattern, two disulfide bridges connect an α-helical segment to the C-terminal strand of a double- or triple-stranded ß-sheet, conforming a cystine-stabilized α/ß scaffold (CSα/ß). Here we show that two K(+) channel-blocking peptides from Tityus scorpions conserve the cysteine spacing of common scorpion venom peptides but display an unconventional disulfide pattern, accompanied by a complete rearrangement of the secondary structure topology into a CS helix-loop-helix fold. Sequence and structural comparisons of the peptides adopting this novel fold suggest that it would be a new elaboration of the widespread CSα/ß scaffold, thus revealing an unexpected structural versatility of these small disulfide-rich proteins. Acknowledgment of such versatility is important to understand how venom structural complexity emerged on a limited number of molecular scaffolds.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Venenos de Escorpião
/
Escorpiões
/
Cisteína
Limite:
Animals
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2012
Tipo de documento:
Article