title: Novel β-1,4-Mannanase Belonging to a New Glycoside Hydrolase Family in Aspergillus nidulans.
abstract: Many filamentous fungi produce β-mannan-degrading β-1,4-mannanases that belong to the glycoside hydrolase 5 (GH5) and GH26 families. Here we identified a novel β-1,4-mannanase (Man134A) that belongs to a new glycoside hydrolase (GH) family (GH134) in Aspergillus nidulans. Blast analysis of the amino acid sequence using the NCBI protein database revealed that this enzyme had no similarity to any sequences and no putative conserved domains. Protein homologs of the enzyme were distributed to limited fungal and bacterial species. Man134A released mannobiose (M2), mannotriose (M3), and mannotetraose (M4) but not mannopentaose (M5) or higher manno-oligosaccharides when galactose-free β-mannan was the substrate from the initial stage of the reaction, suggesting that Man134A preferentially reacts with β-mannan via a unique catalytic mode. Man134A had high catalytic efficiency (kcat/Km) toward mannohexaose (M6) compared with the endo-β-1,4-mannanase Man5C and notably converted M6 to M2, M3, and M4, with M3 being the predominant reaction product. The action of Man5C toward β-mannans was synergistic. The growth phenotype of a Man134A disruptant was poor when β-mannans were the sole carbon source, indicating that Man134A is involved in β-mannan degradation in vivo. These findings indicate a hitherto undiscovered mechanism of β-mannan degradation that is enhanced by the novel β-1,4-mannanase, Man134A, when combined with other mannanolytic enzymes including various endo-β-1,4-mannanases.
authors.affiliation: From the Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan, moshimi@meijo-u.ac.jp.
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Shimizu
authors.affiliation: From the Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan.
authors.forename: Yuhei
authors.initials: Y
authors.lastname: Kaneko
authors.affiliation: From the Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan.
authors.forename: Saaya
authors.initials: S
authors.lastname: Ishihara
authors.affiliation: From the Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan.
authors.forename: Mai
authors.initials: M
authors.lastname: Mochizuki
authors.affiliation: From the Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan.
authors.forename: Kiyota
authors.initials: K
authors.lastname: Sakai
authors.affiliation: From the Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Yamada
authors.affiliation: From the Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Murata
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan, and.
authors.forename: Eriko
authors.initials: E
authors.lastname: Itoh
authors.affiliation: From the Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: From the Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Sugimura
authors.affiliation: From the Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Hirano
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan, and.
authors.forename: Naoki
authors.initials: N
authors.lastname: Takaya
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: From the Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Kato
mesh_terms: D000595:Amino Acid Sequence; D001233:Aspergillus nidulans / Q000201:enzymology* / Q000235:genetics; D002384:Catalysis; D005656:Fungal Proteins / Q000737:chemistry* / Q000145:classification* / Q000235:genetics; D008351:Mannans / Q000737:chemistry; D008361:Mannosidases / Q000737:chemistry* / Q000145:classification* / Q000235:genetics; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry; D010802:Phylogeny; D020539:Sequence Analysis, Protein; D044902:beta-Mannosidase / Q000737:chemistry* / Q000145:classification* / Q000235:genetics
chemical_list: D005656:Fungal Proteins; D008351:Mannans; D009844:Oligosaccharides; C014647:mannobiose; C039922:mannotetraose; C048068:mannopentaose; D008361:Mannosidases; D044902:beta-Mannosidase; C041867:endo-1,4-beta-D-mannanase
keywords: Aspergillus; biodegradation; fungi; glycoside hydrolase; microbiology; oligosaccharide; polysaccharide; transcription regulation