sea anemones toxins i.5-8 kda pore-forming, antihistaminic ii.~20 kda pore-forming equinatoxins,...

Sea Anemones Toxins

I. 5-8 kDa pore-forming, antihistaminic

II. ~20 kDa pore-formingEquinatoxins, sticholysins,

tenebrosins, magnificalysins etc

III. ~30-45 kDa pore-forming, PLA2 activity

IV. 80 kDa pore-formingMetridiolysin (Metridium

senile)

• Sea anemones produce a range of cytolytic peptides

• 4 primary groups:

Sea Anemones Toxins

I. 5-8 kDa pore-forming, antihistaminic

II. ~20 kDa pore-formingEquinatoxins, sticholysins,

tenebrosins, magnificalysins etc

actinoporins

Most numerous and most studied class:Equinatoxins II, IV and V (Actinia equina)Tenebrosins A, B and C (A. tenebrosa)Caritoxin (A. cari)Sticholysins StnI, StnII (Stichodactyla helianthus) and Smt (S. mertensii)Magnificalysins HgmIII, HetI and HetII (Heteractis magnifica)

Pores are formed by oligomers (tri- or tetramers)

High sequence homology within the actinoporin family, common structural properties

All monomeric, no Cys, rich in basic aminoacids

Equinatoxins

Equinatoxins

Sea Anemones Toxins

From Actinia equina L. (European sea anemone)

EqtI

EqtIII

EqtII

EqtIV

EqtV

Equinatoxin II

• -Sandwich structure,2 -helices on each side

• N-terminal region (13-20) essential for cytolysis

• Helix 1 is amphiphilic

• Aromatic patch around W112 and W116, solvent-exposed

Equinatoxin II

• -Sandwich structure,2 -helices on each side

• N-terminal region (13-20) essential for cytolysis

• Helix 1 is amphiphilic

• Aromatic patch around W112 and W116, solvent-exposed

Equinatoxin II

• -Sandwich structure,2 -helices on each side

• N-terminal region (13-20) essential for cytolysis

• Helix 1 is amphiphilic

• Aromatic patch around W112 and W116, solvent-exposed

Equinatoxin II

• -Sandwich structure,2 -helices on each side

• N-terminal region (13-20) essential for cytolysis

• Helix 1 is amphiphilic

• Aromatic patch around W112 and W116, solvent-exposed

• Interaction EqtII-Binding to the membraneNo conformational change

• Interaction EqtII-PC/Insertion into the membrane Major conformational change

• Insertion at raft boundary? • Role of Cholesterol?

Equinatoxin II

StnII, EM @ 15 Å(Mancheño et al, 2003)

W112

PC

No poreReversible

sphingomyeline

Oligomerization (Tetramers) Irreversible

Equinatoxin II: Early Results

QuickTime™ and a decompressor

are needed to see this picture.

15 ns simulation

sphingomyeline (mini raft)(N-stearoylsphingomyeline)

POPC

Typ 112

Typ 116

helix 1 (N-terminal)

helix 2 (C-terminal)

David Poger

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