The crystal structure of diphtheria toxin.
The crystal structure of the diphtheria toxin dimer at 2.5 A resolution reveals a Y-shaped molecule of three domains. The catalytic domain, called fragment A, is of the alpha + beta type. Fragment B actually consists of two domains. The transmembrane domain consists of nine alpha-helices, two pairs of which are unusually apolar and may participate in pH-triggered membrane insertion and translocation. The receptor-binding domain is a flattened beta-barrel with a jelly-roll-like topology. Three distinct functions of the toxin, each carried out by a separate structural domain, can be useful in designing chimaeric proteins, such as immunotoxins, in which the receptor-binding domain is substituted with antibodies to target other cell types.
Choe
S
S
Department of Chemistry and Biochemistry, University of California, Los Angeles 90024.
Bennett
M J
MJ
Fujii
G
G
Curmi
P M
PM
Kantardjieff
K A
KA
Collier
R J
RJ
Eisenberg
D
D
D001427:Bacterial Toxins / Q000737:chemistry; D001665:Binding Sites; D003198:Computer Simulation; D004167:Diphtheria Toxin / Q000737:chemistry*; D007135:Immunoglobulin Variable Region / Q000737:chemistry; D008958:Models, Molecular; D011487:Protein Conformation; D012984:Software; D013816:Thermodynamics; D014961:X-Ray Diffraction
D001427:Bacterial Toxins; D004167:Diphtheria Toxin; D007135:Immunoglobulin Variable Region