Pathways & interactions
Thaumatin family (IPR001938)
Short name: Thaumatin
Overlapping homologous superfamilies
- Osmotin/thaumatin-like superfamily (IPR037176)
Thaumatin [PMID: 7049841] is an intensely sweet-tasting protein, 100 000 times sweeter than sucrose on a molar basis [PMID: 7049841], found in berries from Thaumatococcus daniellii, a tropical flowering plant known as Katemfe. It is induced by attack by viroids, which are single-stranded unencapsulated RNA molecules that do not code for protein.
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 [PMID: 7049841]. Several stress-induced proteins of plants have been found to be related to thaumatins:
- A maize alpha-amylase/trypsin inhibitor
- Two tobacco pathogenesis-related proteins: PR-R major and minor forms,which are induced after infection with viruses
- Salt-induced protein NP24 from tomato
- Osmotin, a salt-induced protein from tobacco[PMID: 16666857]
- Osmotin-like proteins OSML13, OSML15 and OSML81 from potato [PMID: 7630973]
- P21, a leaf protein from soybean
- PWIR2, a leaf protein from wheat [PMID: 1650615]
- Zeamatin, a maize antifunal protein [PMID: 7846159]
This family is also referred to as pathogenesis-related group 5 (PR5), as many thaumatin-like proteins accumulate in plants in response to infection by a pathogen and possess antifungal activity [PMID: 1463856]. The proteins are involved in systematically acquired resistance and stress response in plants, although their precise role is unknown [PMID: 1463856]. The PR5K receptor protein kinase from Arabidopsis comprises an extracellular domain related to the PR5 proteins, and an intracellular protein-serine/threonine kinase domain [PMID: 8637920].