Toxic isolectins from the mushroom Boletus venenatus.
Ingestion of the toxic mushroom Boletus venenatus causes a severe gastrointestinal syndrome, such as nausea, repetitive vomiting, diarrhea, and stomachache. A family of isolectins (B. venenatus lectins, BVLs) was isolated as the toxic principles from the mushroom by successive 80% ammonium sulfate-precipitation, Super Q anion-exchange chromatography, and TSK-gel G3000SW gel filtration. Although BVLs showed a single band on SDS-PAGE, they were further divided into eight isolectins (BVL-1 to -8) by BioAssist Q anion-exchange chromatography. All the isolectins showed lectin activity and had very similar molecular weights as detected by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis. Among them, BVL-1 and -3 were further characterized with their complete amino acid sequences of 99 amino acids determined and found to be identical to each other. In the hemagglutination inhibition assay, both proteins failed to bind to any mono- or oligo-saccharides tested and showed the same sugar-binding specificity to glycoproteins. Among the glycoproteins examined, asialo-fetuin was the strongest inhibitor. The sugar-binding specificity of each isolectin was also analyzed by using frontal affinity chromatography and surface plasmon resonance analysis, indicating that they recognized N-linked sugar chains, especially Galbeta1-->4GlcNAcbeta1-->4Manbeta1-->4GlcNAcbeta1-->4GlcNAc (Type II) residues in N-linked sugar chains. BVLs ingestion resulted in fatal toxicity in mice upon intraperitoneal administration and caused diarrhea upon oral administration in rats.
Horibe
Masashi
M
Department of Applied Biological Chemistry, Faculty of Agriculture, Shizuoka University, Suruga-ku, Shizuoka, Japan.
Kobayashi
Yuka
Y
Dohra
Hideo
H
Morita
Tatsuya
T
Murata
Takeomi
T
Usui
Taichi
T
Nakamura-Tsuruta
Sachiko
S
Kamei
Masugu
M
Hirabayashi
Jun
J
Matsuura
Masanori
M
Yamada
Mina
M
Saikawa
Yoko
Y
Hashimoto
Kimiko
K
Nakata
Masaya
M
Kawagishi
Hirokazu
H
D000363:Agaricales / Q000737:chemistry*; D000595:Amino Acid Sequence; D000818:Animals; D001212:Asialoglycoproteins; D002241:Carbohydrates / Q000737:chemistry; D003967:Diarrhea / Q000139:chemically induced; D004591:Electrophoresis, Polyacrylamide Gel; D060748:Fetuins; D006023:Glycoproteins / Q000737:chemistry; D037102:Lectins / Q000737:chemistry / Q000302:isolation & purification* / Q000633:toxicity; D051379:Mice; D009183:Mycotoxins / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity; D037121:Plant Lectins / Q000737:chemistry / Q000302:isolation & purification* / Q000633:toxicity; D051381:Rats; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D000509:alpha-Fetoproteins
D001212:Asialoglycoproteins; D002241:Carbohydrates; D060748:Fetuins; D006023:Glycoproteins; D037102:Lectins; D009183:Mycotoxins; D037121:Plant Lectins; D000509:alpha-Fetoproteins; C017029:asialofetuin