title: Characterization of the Lentinula edodes exg2 gene encoding a lentinan-degrading exo-beta-1,3-glucanase.
abstract: Lentinan, an antitumor substance purified from Lentinula edodes, is degraded during post-harvest preservation as a result of increased glucanase activity. We isolated an exo-beta-1,3-glucanase encoding gene, exg2, from L. edodes which is a homologue of an exo-glucanase-encoding gene conserved in ascomycetous fungi. The exg2 gene was cloned as an approximately 2.4-kbp cDNA, and as a genomic sequence of 3.9-kbp. The product of the exg2 gene is predicted to contain 759 amino acids with a molecular weight of 79 kDa and a pI value of 4.6. The putative N-terminus of EXG2 is identical to the N-terminal sequences of lentinan-degrading enzymes, GNase I and II, and a custom-made anti-EXG2 peptide anti-serum cross-reacted with purified GNase I and II. Transcription and translation of exg2 was low in the gills of mature fruiting bodies, but increased after harvesting. We conclude that the exg2 gene is a lentinan-degrading enzyme-encoding-gene in L. edodes.
authors.affiliation: Iwate Biotechnology Research Center, 22-174-4 Narita, Kitakami-shi, Iwate, 024-0003 Japan. sakamoto@ibrc.or.jp
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Sakamoto
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Minato
authors.forename: Masaru
authors.initials: M
authors.lastname: Nagai
authors.forename: Masashi
authors.initials: M
authors.lastname: Mizuno
authors.forename: Toshitsugu
authors.initials: T
authors.lastname: Sato
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D015153:Blotting, Western; D003001:Cloning, Molecular; D017124:Conserved Sequence; D005800:Genes, Fungal; D043326:Glucan 1,3-beta-Glucosidase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D007912:Lentinan / Q000378:metabolism; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D020942:Shiitake Mushrooms / Q000201:enzymology / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D007912:Lentinan; D043326:Glucan 1,3-beta-Glucosidase