Abstract
Acetyl xylan esterase (AXE) catalyzes the hydrolysis of the acetyl bonds present in plant cell wall polysaccharides. Here, we determined the crystal structure of AXE from Aspergillus luchuensis (AlAXEA), providing the three-dimensional structure of an enzyme in the Esterase_phb family. AlAXEA shares its core α/β-hydrolase fold structure with esterases in other families, but it has an extended central β-sheet at both its ends and an extra loop. Structural comparison with a ferulic acid esterase (FAE) from Aspergillus niger indicated that AlAXEA has a conserved catalytic machinery: a catalytic triad (Ser119, His259, and Asp202) and an oxyanion hole (Cys40 and Ser120). Near the catalytic triad of AlAXEA, two aromatic residues (Tyr39 and Trp160) form small pockets at both sides. Homology models of fungal FAEs in the same Esterase_phb family have wide pockets at the corresponding sites because they have residues with smaller side chains (Pro, Ser, and Gly). Mutants with sitedirected mutations at Tyr39 showed a substrate specificity similar to that of the wild-type enzyme, whereas those with mutations at Trp160 acquired an expanded substrate specificity. Interestingly, the Trp160 mutants acquired weak but significant type B-like FAE activity. Moreover, the engineered enzymes exhibited ferulic acid-releasing activity from wheat arabinoxylan.
| Original language | English |
|---|---|
| Article number | e01251-17 |
| Journal | Applied and Environmental Microbiology |
| Volume | 83 |
| Issue number | 20 |
| Early online date | 2017 |
| DOIs | |
| Publication status | Published - 2017 |
| MoE publication type | A1 Journal article-refereed |
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Keywords
- aspergillus luchuensis
- carboxylesterase
- catalytic triad
- enzyme structure
- ESTHER database
- X-ray crystallography
- a/ß-hydrolase fold
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Crystal structure and substrate specificity modification of acetyl xylan esterase from Aspergillus luchuensis. / Komiya, Dai; Hori, Akane; Ishida, Takuya; Igarashi, Kiyohiko; Samejima, Masahiro; Koseki, Takuya; Fushinobu, Shinya.
In: Applied and Environmental Microbiology, Vol. 83, No. 20, e01251-17, 2017.Research output: Contribution to journal › Article › Scientific › peer-review
TY - JOUR
T1 - Crystal structure and substrate specificity modification of acetyl xylan esterase from Aspergillus luchuensis
AU - Komiya, Dai
AU - Hori, Akane
AU - Ishida, Takuya
AU - Igarashi, Kiyohiko
AU - Samejima, Masahiro
AU - Koseki, Takuya
AU - Fushinobu, Shinya
PY - 2017
Y1 - 2017
N2 - Acetyl xylan esterase (AXE) catalyzes the hydrolysis of the acetyl bonds present in plant cell wall polysaccharides. Here, we determined the crystal structure of AXE from Aspergillus luchuensis (AlAXEA), providing the three-dimensional structure of an enzyme in the Esterase_phb family. AlAXEA shares its core α/β-hydrolase fold structure with esterases in other families, but it has an extended central β-sheet at both its ends and an extra loop. Structural comparison with a ferulic acid esterase (FAE) from Aspergillus niger indicated that AlAXEA has a conserved catalytic machinery: a catalytic triad (Ser119, His259, and Asp202) and an oxyanion hole (Cys40 and Ser120). Near the catalytic triad of AlAXEA, two aromatic residues (Tyr39 and Trp160) form small pockets at both sides. Homology models of fungal FAEs in the same Esterase_phb family have wide pockets at the corresponding sites because they have residues with smaller side chains (Pro, Ser, and Gly). Mutants with sitedirected mutations at Tyr39 showed a substrate specificity similar to that of the wild-type enzyme, whereas those with mutations at Trp160 acquired an expanded substrate specificity. Interestingly, the Trp160 mutants acquired weak but significant type B-like FAE activity. Moreover, the engineered enzymes exhibited ferulic acid-releasing activity from wheat arabinoxylan.
AB - Acetyl xylan esterase (AXE) catalyzes the hydrolysis of the acetyl bonds present in plant cell wall polysaccharides. Here, we determined the crystal structure of AXE from Aspergillus luchuensis (AlAXEA), providing the three-dimensional structure of an enzyme in the Esterase_phb family. AlAXEA shares its core α/β-hydrolase fold structure with esterases in other families, but it has an extended central β-sheet at both its ends and an extra loop. Structural comparison with a ferulic acid esterase (FAE) from Aspergillus niger indicated that AlAXEA has a conserved catalytic machinery: a catalytic triad (Ser119, His259, and Asp202) and an oxyanion hole (Cys40 and Ser120). Near the catalytic triad of AlAXEA, two aromatic residues (Tyr39 and Trp160) form small pockets at both sides. Homology models of fungal FAEs in the same Esterase_phb family have wide pockets at the corresponding sites because they have residues with smaller side chains (Pro, Ser, and Gly). Mutants with sitedirected mutations at Tyr39 showed a substrate specificity similar to that of the wild-type enzyme, whereas those with mutations at Trp160 acquired an expanded substrate specificity. Interestingly, the Trp160 mutants acquired weak but significant type B-like FAE activity. Moreover, the engineered enzymes exhibited ferulic acid-releasing activity from wheat arabinoxylan.
KW - aspergillus luchuensis
KW - carboxylesterase
KW - catalytic triad
KW - enzyme structure
KW - ESTHER database
KW - X-ray crystallography
KW - a/ß-hydrolase fold
UR - http://www.scopus.com/inward/record.url?scp=85030699408&partnerID=8YFLogxK
U2 - 10.1128/AEM.01251-17
DO - 10.1128/AEM.01251-17
M3 - Article
VL - 83
JO - Applied and Environmental Microbiology
JF - Applied and Environmental Microbiology
SN - 0099-2240
IS - 20
M1 - e01251-17
ER -