title: Molecular cloning, expression, and characterization of novel hemolytic lectins from the mushroom Laetiporus sulphureus, which show homology to bacterial toxins.
abstract: We describe herein the cDNA cloning, expression, and characterization of a hemolytic lectin and its related species from the parasitic mushroom Laetiporus sulphureus. The lectin designated LSL (L. sulphureus lectin), is a tetramer composed of subunits of approximately 35 kDa associated by non-covalent bonds. From a cDNA library, three similar full-length cDNAs, termed LSLa, LSLb, and LSLc, were generated, each of which had an open reading frame of 945 bp encoding 315 amino acid residues. These proteins share 80-90% sequence identity and showed structural similarity to bacterial toxins: mosquitocidal toxin (MTX2) from Bacillus sphaericus and alpha toxin from Clostridium septicum. Native and recombinant forms of LSL showed hemagglutination and hemolytic activity and both activities were inhibited by N-acetyllactosamine, whereas a C-terminal deletion mutant of LSLa (LSLa-D1) retained hemagglutination, but not hemolytic activity, indicating the N-terminal domain is a carbohydrate recognition domain and the C-terminal domain functions as an oligomerization domain. The LSL-mediated hemolysis was protected osmotically by polyethylene glycol 4000 and maltohexaose. Inhibition studies showed that lacto-N-neotetraose (Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc) was the best inhibitor for LSL. These results indicate that LSL is a novel pore-forming lectin homologous to bacterial toxins.
authors.affiliation: Department of Biological Chemistry, the University of Michigan Medical School, Ann Arbor, Michigan 48109-0606, USA.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Tateno
authors.forename: Irwin J
authors.initials: IJ
authors.lastname: Goldstein
mesh_terms: D000363:Agaricales / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry; D001427:Bacterial Toxins / Q000737:chemistry / Q000378:metabolism*; D002241:Carbohydrates / Q000737:chemistry; D002942:Circular Dichroism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D015723:Gene Library; D006241:Haptens / Q000737:chemistry; D006384:Hemagglutination; D006461:Hemolysis; D020128:Inhibitory Concentration 50; D037102:Lectins / Q000737:chemistry*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D009995:Osmosis; D010455:Peptides / Q000737:chemistry; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D000596:Amino Acids; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D002241:Carbohydrates; D018076:DNA, Complementary; D006241:Haptens; D037102:Lectins; C099210:Mtx2 protein, Bacillus sphaericus; D010455:Peptides; D011994:Recombinant Proteins; C064270:hemolytic toxin, Clostridium septicum