Resolution of the structure of the allergenic and antifungal banana fruit thaumatin-like protein at 1.7-A.
The structure of a thaumatin-like protein from banana (Musa acuminata) fruit, an allergen with antifungal properties, was solved at 1.7-A-resolution, by X-ray crystallography. Though the banana protein exhibits a very similar overall fold as thaumatin it markedly differs from the sweet-tasting protein by the presence of a surface exposed electronegative cleft. Due to the presence of this electronegative cleft, the banana thaumatin-like protein (Ban-TLP) acquires a strong (local) electronegative character that eventually explains the observed antifungal activity. Our structural analysis also revealed the presence of conserved residues of exposed epitopic determinants that are presumably responsible for the allergenic properties of banana fruit towards susceptible individuals, and provided evidence that the Ban-TLP shares some structurally highly conserved IgE-binding epitopes with thaumatin-like proteins from fruits or pollen from other plants. In addition, some overlap was detected between the predicted IgE-binding epitopes of the Ban-TLP and IgE-binding epitopes previously identified in the mountain cedar Jun a 3 TLP aeroallergen. The presence of these common epitopes offers a molecular basis for the cross-reactivity between aeroallergens and fruit allergens.
Leone
Philippe
P
Architecture et fonction des macromolécules biologiques, UMR-CNRS, 31, chemin Joseph-Aiguier, 13402 Marseille cedex 20, France.
Menu-Bouaouiche
Laurence
L
Peumans
Willy J
WJ
Payan
Françoise
F
Barre
Annick
A
Roussel
Alain
A
Van Damme
Els J M
EJ
Rougé
Pierre
P
D000485:Allergens / Q000737:chemistry*; D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D000939:Epitopes; D007073:Immunoglobulin E / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry*; D016415:Sequence Alignment
D000485:Allergens; D000935:Antifungal Agents; D000939:Epitopes; D010940:Plant Proteins; C420118:thaumatin-like protein, Musa acuminata; D007073:Immunoglobulin E