The structure of a Staphylococcus aureus leucocidin component (LukF-PV) reveals the fold of the water-soluble species of a family of transmembrane pore-forming toxins.
BACKGROUND
Leucocidins and gamma-hemolysins are bi-component toxins secreted by Staphylococcus aureus. These toxins activate responses of specific cells and form lethal transmembrane pores. Their leucotoxic and hemolytic activities involve the sequential binding and the synergistic association of a class S and a class F component, which form hetero-oligomeric complexes. The components of each protein class are produced as non-associated, water-soluble proteins that undergo conformational changes and oligomerization after recognition of their cell targets.


RESULTS
The crystal structure of the monomeric water-soluble form of the F component of Panton-Valentine leucocidin (LukF-PV) has been solved by the multiwavelength anomalous dispersion (MAD) method and refined at 2.0 A resolution. The core of this three-domain protein is similar to that of alpha-hemolysin, but significant differences occur in regions that may be involved in the mechanism of pore formation. The glycine-rich stem, which undergoes a major rearrangement in this process, forms an additional domain in LukF-PV. The fold of this domain is similar to that of the neurotoxins and cardiotoxins from snake venom.


CONCLUSIONS
The structure analysis and a multiple sequence alignment of all toxic components, suggest that LukF-PV represents the fold of any water-soluble secreted protein in this family of transmembrane pore-forming toxins. The comparison of the structures of LukF-PV and alpha-hemolysin provides some insights into the mechanism of transmembrane pore formation for the bi-component toxins, which may diverge from that of the alpha-hemolysin heptamer.
Pédelacq
J D
JD
Groupe de Cristallographie Biologique Institut de Pharmacologie et de Biologie Structurale du CNRS 205 route de Narbonne 31077 Toulouse Cedex France.
Maveyraud
L
L
Prévost
G
G
Baba-Moussa
L
L
González
A
A
Courcelle
E
E
Shepard
W
W
Monteil
H
H
Samama
J P
JP
Mourey
L
L
D000595:Amino Acid Sequence; D001427:Bacterial Toxins / Q000737:chemistry; D002462:Cell Membrane / Q000648:ultrastructure; D002463:Cell Membrane Permeability / Q000187:drug effects; D018360:Crystallography, X-Ray; D005098:Exotoxins; D006460:Hemolysin Proteins / Q000737:chemistry; D007956:Leukocidins / Q000737:chemistry* / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012995:Solubility; D013211:Staphylococcus aureus / Q000737:chemistry*; D013329:Structure-Activity Relationship
D001427:Bacterial Toxins; D005098:Exotoxins; D006460:Hemolysin Proteins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin; C021091:staphylococcal alpha-toxin