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Title: Specific binding of victorin to a 100-kDa protein from oats

Susceptibility of oats to victoria blight, caused by the fungus Cochliobolus victoriae, and sensitivity to the host-specific toxin victorin, produced by the fungus, are controlled by the dominant allele at the Vb locus. It has been postulated that the Vb locus encodes a toxin receptor, although direct evidence for such a receptor is not available. Recent studies on structure-activity relationships of the toxin established a methodology for producing {sup 125}I-labeled victorin. Electrophoretic analysis of proteins from isogenic susceptible and resistant oat genotypes following treatment of leaves with radiolabeled victorin showed that victorin binds in a covalent and a genotype-specific manner to a 100-kDa protein only in susceptible oat leaf slices. This in vivo binding was competitively displaced by reduced victorin, a nontoxic protective compound, and appeared to be correlated with biological activity. In vitro binding to the 100-kDa protein in leaf extracts showed several differences from in vivo binding. Binding was not genotype specific and required a reducing agent that was not required for in vivo binding. Differential centrifugation showed that the 100-kDa victorin binding protein was not a cytosolic protein but was enriched in a high-speed particulate fraction. The data support the hypothesis that the 100-kDa protein is themore » victorin receptor.« less
Authors:
;  [1]
  1. (Cornell Univ., Ithaca, NY (USA))
Publication Date:
OSTI Identifier:
5264406
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proceedings of the National Academy of Sciences of the United States of America; (USA); Journal Volume: 86:11
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; MEMBRANE PROTEINS; CROSS-LINKING; RECEPTORS; MOLECULAR STRUCTURE; TOXINS; AUTORADIOGRAPHY; DOSE-RESPONSE RELATIONSHIPS; ELECTROPHORESIS; FUNGAL DISEASES; GENOTYPE; IODINE 125; LABELLED COMPOUNDS; MEMBRANES; OATS; PROTEINS; ANTIGENS; BETA DECAY RADIOISOTOPES; CEREALS; CHEMICAL REACTIONS; DAYS LIVING RADIOISOTOPES; DISEASES; ELECTRON CAPTURE RADIOISOTOPES; GRASS; INFECTIOUS DISEASES; INTERMEDIATE MASS NUCLEI; IODINE ISOTOPES; ISOTOPES; LILIOPSIDA; MAGNOLIOPHYTA; MATERIALS; NUCLEI; ODD-EVEN NUCLEI; ORGANIC COMPOUNDS; PLANTS; POLYMERIZATION; RADIOISOTOPES; TOXIC MATERIALS 550201* -- Biochemistry-- Tracer Techniques