Characterization of two distinct feruloyl esterases, AoFaeB and AoFaeC, from Aspergillus oryzae

• Published in: Applied microbiology and biotechnology 2009-06, Vol.83 (4), p.689-696
• Main Authors: Koseki, Takuya, Hori, Akane, Seki, Shouji, Murayama, Tetsuya, Shiono, Yoshihito
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Aspergillus oryzae; Aspergillus oryzae - enzymology; Aspergillus oryzae - genetics; Aspergillus oryzae - metabolism; Biological and medical sciences; Biotechnologically Relevant Enzymes and Proteins; Biotechnology; Carboxylic Ester Hydrolases - chemistry; Carboxylic Ester Hydrolases - genetics; Carboxylic Ester Hydrolases - isolation & purification; Carboxylic Ester Hydrolases - metabolism; Chlorogenic Acid - metabolism; Cloning; Cloning, Molecular; Coumaric Acids - metabolism; Enzyme kinetics; Enzyme Stability; Enzymes; ferulic acid; Feruloyl esterase; Fundamental and applied biological sciences. Psychology; Fungal Proteins - chemistry; Fungal Proteins - genetics; Fungal Proteins - isolation & purification; Fungal Proteins - metabolism; Gene Expression; Genes; Hydrogen-Ion Concentration; Investigations; Life Sciences; Microbial Genetics and Genomics; Microbiology; Molecular Sequence Data; Molecular Weight; Pichia - genetics; Plant cell wall; Proteins; Recombinant Proteins - genetics; Recombinant Proteins - isolation & purification; Recombinant Proteins - metabolism; Sequence Alignment; Sodium; Studies; Substrate Specificity; Temperature; Xylans - metabolism
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-009-1913-z

Two hypothetical proteins XP_001818628 and XP_001819091 (designated AoFaeB and AoFaeC, respectively), showing sequence identity with known type-C feruloyl esterases, have been found in the genomic sequence of Aspergillus oryzae. We cloned the putative A. oryzae feruloyl esterase-encoding genes and expressed them in Pichia pastoris. Both purified recombinant AoFaeB (rAoFaeB) and AoFaeC (rAoFaeC) had apparent relative molecular masses of 61,000 and 75,000, respectively, on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. After N-deglycosylation, both proteins had a relative molecular mass of 55,000. The optimum pH for rAoFaeB was 6.0, although it was stable at pH values ranging from 3.0 to 9.0; rAoFaeC had an optimum pH of 6.0 and was stable in the pH range of 7.0-10.0. Thermostability of rAoFaeC was greater than that of rAoFaeB. Whereas rAoFaeC displayed hydrolytic activity toward methyl caffeate, methyl p-coumarate, methyl ferulate, and methyl sinapate, rAoFaeB displayed hydrolytic activity toward methyl caffeate, methyl p-coumarate, and methyl ferulate but not toward methyl sinapate. Substrate specificity profiling of rAoFaeB and rAoFaeC revealed type-B and type-C feruloyl esterases, respectively. Ferulic acid was efficiently released from wheat arabinoxylan when both esterases were applied with xylanase from Thermomyces lanuginosus. Both recombinant proteins also exhibited hydrolytic activity toward chlorogenic acid.