Isolation and partial characterization of two antifungal proteins from barley

• Published in: Biochimica et biophysica acta Vol. 880; no. 2; pp. 161 - 170
• Main Authors: Roberts, Walden K., Selitrennikoff, Claude P.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 19.02.1986; Elsevier; North-Holland
• Subjects: Antibiotics. Antiinfectious agents. Antiparasitic agents; Antifungal agents; Antifungal Agents - isolation & purification; Antifungal protein; Barley; Biological and medical sciences; characterization; Chromatography, Gel; Defense mechanism; Edible Grain - analysis; Electrophoresis, Polyacrylamide Gel; Fungi - drug effects; Fungi - growth & development; Hordeum - analysis; Hordeum vulgare; isolation; Medical sciences; Microbial Sensitivity Tests; Molecular Weight; Pharmacology. Drug treatments; Plant Proteins - isolation & purification; Plant Proteins - pharmacology; proteins; Ribosome-inactivating protein; Temperature; Barley; Defense mechanism; Ribosome-inactivating protein; Antifungal protein; Microorganism growth; Ribosome; Phycomycetes; Alternaria; Fungistasis; Phycomyces blakesleeanus; Host agent relation; Trichoderma reesei; Biological activity; Fungicide; Characterization; Fungi; Proteins; Plant origin; Ascomycetes; Neurospora crassa; Fungi Imperfecti; Inhibition; Mechanism of action; Thallophyta
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/0304-4165(86)90076-0

We have developed a simple assay for detecting antifungal compounds utilizing impregnated paper discs on agar to inhibit mycelial spread of an indicator organism, richoderma reesei isolated and purified to apparent homogeneity two antifungal proteins from dehusked barley grain. Both proteins are present at high concentrations: over 10 mg of each protein can be isolated per 100 g of grain. The first protein has a molecular weight of 30 000 and is identical to the 30 kDa ribosome-inactivating protein previously isolated from barley. This protein very effectively inactivates fungal ribosomes and this may explain its antifungal activity and biological role. The second antifungal protein has a molecular weight of 28 000 and is 20-fold more potent than the 30 kDa protein in inhibiting growth of Trichoderma. In addition to Trichoderma, the 28 kDa protein also efficiently inhibits growth of Phycomyces blakesleeanus, Alternaria alternaria and a protoplast-forming mutant of Neurospora crassa. The 28 kDa protein does not inactivate fungal ribosomes and we are currently investigating other possible enzymatic activities of this protein.