title: An Aspergillus oryzae acetyl xylan esterase: molecular cloning and characteristics of recombinant enzyme expressed in Pichia pastoris.
abstract: We screened 20,000 clones of an expressed sequence tag (EST) library from Aspergillus oryzae (http://www.nrib.go.jp/ken/EST/db/index.html) and obtained one cDNA clone encoding a protein with similarity to fungal acetyl xylan esterase. We also cloned the corresponding gene, designated as Aoaxe, from the genomic DNA. The deduced amino acid sequence consisted of a putative signal peptide of 31-amino acids and a mature protein of 276-amino acids. We engineered Aoaxe for heterologous expression in P. pastoris. Recombinant AoAXE (rAoAXE) was secreted by the aid of fused alpha-factor secretion signal peptide and accumulated as an active enzyme in the culture medium to a final level of 190 mg/l after 5 days. Purified rAoAXEA before and after treatment with endoglycosidase H migrated by SDS-PAGE with a molecular mass of 31 and 30 kDa, respectively. Purified rAoAXE displayed the greatest hydrolytic activity toward alpha-naphthylacetate (C2), lower activity toward alpha-naphthylpropionate (C3) and no detectable activity toward acyl-chain substrates containing four or more carbon atoms. The recombinant enzyme catalyzed the release of acetic acid from birchwood xylan. No activity was detectable using methyl esters of ferulic, caffeic or sinapic acids. rAoAXE was thermolabile in comparison to other AXEs from Aspergillus.
authors.affiliation: National Research Institute of Brewing, 3-7-1 Kagamiyama, Higashi-Hiroshima 739-0046, Japan. tkoseki@nrib.go.jp
authors.forename: Takuya
authors.initials: T
authors.lastname: Koseki
authors.forename: Yozo
authors.initials: Y
authors.lastname: Miwa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Akao
authors.forename: Osamu
authors.initials: O
authors.lastname: Akita
authors.forename: Katsumi
authors.initials: K
authors.lastname: Hashizume
mesh_terms: D000115:Acetylesterase / Q000032:analysis / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D000595:Amino Acid Sequence; D001236:Aspergillus oryzae / Q000201:enzymology* / Q000235:genetics; D001483:Base Sequence; D002384:Catalysis; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D005818:Genetic Engineering; D006863:Hydrogen-Ion Concentration; D015151:Immunoblotting; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010843:Pichia / Q000235:genetics; D021382:Protein Sorting Signals; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013696:Temperature; D013997:Time Factors
chemical_list: D005656:Fungal Proteins; D021382:Protein Sorting Signals; D011994:Recombinant Proteins; D000115:Acetylesterase; C081851:acetylxylan esterase