Two antifungal thaumatin‐like proteins from barley grain

Abstract

Antifungal activity has been associated with 2 immunochemically distinct proteins, protein R and S (M, -23 kDa; pI g-10), which were isolated in pure form from barley grain. The proteins are homologous with thaumatin-and pathogenesis-related proteins of the PW family. The proteins inhibit growth of i.a. Trichodermu viri& and Can&/~ a&cans 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 ol-amylases or serine proteases could be associated with protein R or S the results indicate that the homologous maize grain bifunctional inhibitor of insect a-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.

Study of the Intercellular Fluid of Healthy Lupinus albus Organs (Presence of a Chitinase and a Thaumatin-Like Protein)

“…No homology was found between the amino-terminal amino acid sequence from IF4 Figure 2. Comparison of the amino-terminal amino acid residues of IF1 with those of an antifungal protein from barley (BP-R) (Hejgaard et al, 1991). X, No amino acid derivative was detected by HPLC.…”

“…IF1 (Fig. 2) had 70% identical (80% similar) amino acid residues to an antifungal protein (BP-R) from Hordeum vulgare (Hejgaard et al, 1991), which belongs to the thaumatin family (PR-5 family). The 16 amino-terminal amino acid residues from IF3 also had strong identity to those of previously reported class III chitinase-lysozymes, as shown in Figure 3.…”

A Review: Biological and Technological Functions of Barley Seed Pathogenesis-Related Proteins (PRs)

“…Barley seed TLPs inhibit growth of T. viride, Candida albicans 67,127 , Micrococcus lysodeikticus and F. sporotrichioides 109 . In situ concentration of both isoforms is much higher than required for Fusarium growth inhibition 109 .…”

“…Several isoforms of TLP have been detected in barley leaves 277 and two isoforms have been found in barley seed 67,109,127 . They fall into two groups, long and short chain proteins, with 16 and 10 cysteine residues respectively 278 .…”

“…They fall into two groups, long and short chain proteins, with 16 and 10 cysteine residues respectively 278 . Two highly homologous basic isoforms from barley seed, named TLP-S and TLP-R in accordance with the nomenclature used for tobacco proteins 127 , belong to the first group. Expression of TLPs switches from the ovary wall to the aleurone in developing barley seeds, following a unique bimodal pattern of expression.…”