Distinction between pore assembly by staphylococcal alpha-toxin versus leukotoxins.
The staphylococcal bipartite leukotoxins and the homoheptameric alpha-toxin belong to the same family of beta-barrel pore-forming toxins despite slight differences. In the alpha-toxin pore, the N-terminal extremity of each protomer interacts as a deployed latch with two consecutive protomers in the vicinity of the pore lumen. N-terminal extremities of leukotoxins as seen in their three-dimensional structures are heterogeneous in length and take part in the beta-sandwich core of soluble monomers. Hence, the interaction of these N-terminal extremities within structures of adjacent monomers is questionable. We show here that modifications of their N-termini by two different processes, using fusion with glutathione S-transferase (GST) and bridging of the N-terminal extremity to the adjacent beta-sheet via disulphide bridges, are not deleterious for biological activity. Therefore, bipartite leukotoxins do not need a large extension of their N-terminal extremities to form functional pores, thus illustrating a microheterogeneity of the structural organizations between bipartite leukotoxins and alpha-toxin.
Joubert
Olivier
O
Laboratoire de Physiopathologie et d'Antibiologie des Infections Bactériennes Emergentes et Nosocomiales, EA 3432, Institut de Bactériologie de la Faculté de Médecine, Université Louis Pasteur-Hôpitaux Universitaires de Strasbourg, 67000 Strasbourg, France.
Voegelin
Joëlle
J
Guillet
Valérie
V
Tranier
Samuel
S
Werner
Sandra
S
Colin
Didier A
DA
Dalla Serra
Mauro
M
Keller
Daniel
D
Monteil
Henri
H
Mourey
Lionel
L
Prévost
Gilles
G