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Two antifungal thaumatin‐like proteins from barley grain
Author(s) -
Hejgaard Jørn,
Jacobsen Susanne,
Svendsen Ib
Publication year - 1991
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(91)81119-s
Subject(s) - thaumatin , antifungal , chemistry , biochemistry , food science , microbiology and biotechnology , biology , gene
Antifungal activity has been associated with 2 immunochemically distinct proteins, protein R and S ( M r ∼23 kDa; pI 9‐10), which were isolated in pure form from barley grain. The proteins are homologous with thaumatin‐ and pathogenesis‐related proteins of the PR5 family. The proteins inhibit growth of i.a. Trichoderma viride and Candida albicans in microtiter plate assays and act synergistically with barley grain chitinase C. Like maize zeamatin, protein R and S but not chitinase C retarded fungal growth in synergism with nikkomycin Z, a nucleoside‐peptide inhibitor of fungal chitin synthesis. Although no inhibition of α‐amylases or serine proteases could be associated with protein R or S the results indicate that the homologous maize grain bifunctional inhibitor of insect α‐amylase and trypsin is very similar to or identical with maize zeamatin, which was proposed to have permeabilizing activity towards fungal membranes. Thus, in addition to the intensely sweet properties of thaumatin, multiple unrelated defense functions against insect and fungal pests can now be associated with the family of thaumatin‐homologous proteins.