InterPro domain: IPR037176

Thaumatin [ 1 ] is an intensely sweet-tasting protein, 100 000 times sweeter than sucrose on a molar basis [ 2 ] found in berries from Thaumatococcus daniellii, a tropical flowering plant known as Katemfe. When attacked by viroids, single-stranded unencapsulated RNA molecules that do not code for protein, thaumatin is induced.

Thaumatin consists of about 200 residues and contains 8 disulphide bonds. Like other PR proteins, thaumatin is predicted to have a mainly beta structure, with a high content of beta-turns and little helix [ 2 ].

Osmotin belongs to the PR-5 protein family whose members are homologous to thaumatin. Osmotin and other PR-5 proteins were shown to have antifungal activity in vitro against a broad range of fungi, including several plant pathogens[ 2 ].

1. Cloning of cDNA encoding the sweet-tasting plant protein thaumatin and its expression in Escherichia coli. Gene 18, 1-12
2. Crystal structure of osmotin, a plant antifungal protein. Proteins 54, 170-3