Ion channels and bacterial infection: the case of β‐barrel pore‐forming protein toxins of Staphylococcus aureus

FEBS Letters

Viero, G¹  Coraiola, M¹  Dalla Serra, M¹  Menestrina, G¹  Comai, M¹  Prévost, G²  Colin, D.A²  Monteil, H²  Werner, S³ 

[1] CNR-ITC Istituto di Biofisica, Sezione di Trento, Via Sommarive 18, I-38050 Povo, Italy;Institut de Bactériologie de la Faculté de Médecine, UPRES EA-3432, ULP-HUS, 3 rue Koeberlé, F-67000 Strasbourg, France;INSERM-U544, Institut de Virologie de la Faculté de Médecine, ULP-HUS, 3 rue Koeberlé, F-67000 Strasbourg, France

关键词: α-Hemolysin;    Bicomponent leukotoxin;    γ-Hemolysin;    Oligomerization;    Ion selectivity;    Pore size;    EM;    electron microscopy;    Et;    ethidium;    PC;    phosphatidylcholine;    PEG;    polyethylene glycol;    PFT;    pore-forming toxins;    PMA;    phorbol myristyl acetate;    PMN;    polymorphonuclear cells;    PVL;    Panton–Valentine leukocidins;    RBC;    red blood cells;   

DOI  :  10.1016/S0014-5793(03)00850-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Staphylococcus aureus strains causing human pathologies produce several toxins, including a pore-forming protein family formed by the single-component α-hemolysin and the bicomponent leukocidins and γ-hemolysins. The last comprise two protein elements, S and F, that co-operatively form the active toxin. α-Hemolysin is always expressed by S. aureus strains, whereas bicomponent leukotoxins are more specifically involved in a few diseases. X-ray crystallography of the α-hemolysin pore has shown it is a mushroom-shaped, hollow heptamer, almost entirely consisting of β-structure. Monomeric F subunits have a very similar core structure, except for the transmembrane stem domain which has to refold during pore formation. Large deletions in this domain abolished activity, whereas shorter deletions sometimes improved it, possibly by removing some of the interactions stabilizing the folded structure. Even before stem extension is completed, the formation of an oligomeric pre-pore can trigger Ca²⁺-mediated activation of some white cells, initiating an inflammatory response. Within the bicomponent toxins, γ-hemolysins define three proteins (HlgA, HlgB, HlgC) that can generate two toxins: HlgA+HlgB and HlgC+HlgB. Like α-hemolysin they form pores in planar bilayers with similar conductance, but opposite selectivity (cation instead of anion) for the presence of negative charges in the ion pathway. γ-Hemolysin pores seem to be organized as α-hemolysin, but should contain an even number of each component, alternating in a 1:1 stoichiometry.

【 授权许可】

Unknown