Several thaumatin-like proteins bind to beta-1,3-glucans.
Pathogenesis-related proteins from intercellular fluid washings of stressed barley (Hordeum vulgare L.) leaves were analyzed to determine their binding to various water-insoluble polysaccharides. Three proteins (19, 16, and 15 kD) bound specifically to several water-insoluble beta-1,3-glucans. Binding of the barley proteins to pachyman occurred quickly at 22 degreesC at pH 5.0, even in the presence of 0.5 M NaCl, 0.2 M urea, and 1% (v/v) Triton X-100. Bound barley proteins were released by acidic treatments or by boiling in sodium dodecyl sulfate. Acid-released barley proteins could bind again specifically and singly to pachyman. Water-soluble laminarin and carboxymethyl-pachyman competed for the binding of the barley proteins to pachyman. The N-terminal sequence of the 19-kD barley beta-1,3-glucan-binding protein showed near identity to the barley seed protein BP-R and high homology to other thaumatin-like (TL) permatins. The 16-kD barley protein was also homologous to TL proteins, whereas the 15-kD barley protein N-terminal sequence was identical to the pathogenesis-related Hv-1 TL protein. Antifungal barley protein BP-R and corn (Zea mays) zeamatin were isolated by binding to pachyman. Two extracellular proteins from stressed pea (Pisum sativum L.) also bound to pachyman and were homologous to TL proteins.
Trudel
J
J
Département de Phytologie, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université Laval, Québec, Canada G1K 7P4.
Grenier
J
J
Potvin
C
C
Asselin
A
A
D000595:Amino Acid Sequence; D005936:Glucans / Q000378:metabolism*; D001467:Hordeum / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid; D012995:Solubility; D013549:Sweetening Agents; D047071:beta-Glucans
D005936:Glucans; D010940:Plant Proteins; D013549:Sweetening Agents; D047071:beta-Glucans; C003427:thaumatin protein, plant; C014731:pachyman; C033363:beta-1,3-glucan