A novel acetyl xylan esterase enabling complete deacetylation of substituted xylans

Fakhria M. Razeq, Edita Jurak, Peter J. Stogios, Ruoyu Yan, Maija Tenkanen, Mirjam A. Kabel, Weijun Wang, Emma R. Master*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

13 Citations (Scopus)
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Abstract

Background: Acetylated 4-O-(methyl) glucuronoxylan (GX) is the main hemicellulose in deciduous hardwood, and comprises a beta-(1 -> 4)-linked xylopyranosyl (Xylp) backbone substituted by both acetyl groups and alpha-(1 -> 2)-linked 4-O-methylglucopyranosyluronic acid (MeGlcpA). Whereas enzymes that target singly acetylated Xylp or doubly 2,3-O-acetyl-Xylp have been well characterized, those targeting (2-O-MeGlcpA) 3-O-acetyl-Xylp structures in glucuronoxylan have remained elusive.

Results: An unclassified carbohydrate esterase (FjoAcXE) was identified as a protein of unknown function from a polysaccharide utilization locus (PUL) otherwise comprising carbohydrate-active enzyme families known to target xylan. FjoAcXE was shown to efficiently release acetyl groups from internal (2-O-MeGlcpA) 3-O-acetyl-Xylp structures, an activity that has been sought after but lacking in known carbohydrate esterases. FjoAcXE action boosted the activity of alpha-glucuronidases from families GH67 and GH115 by five and nine times, respectively. Moreover, FjoAcXE activity was not only restricted to GX, but also deacetylated (3-O-Araf)2-O-acetyl-Xylp of feruloylated xylooligomers, confirming the broad substrate range of this new carbohydrate esterase.

Conclusion: This study reports the discovery and characterization of the novel carbohydrate esterase, FjoAcXE. In addition to cleaving singly acetylated Xylp, and doubly 2,3-O-acetyl-Xylp, FjoAcXE efficiently cleaves internal 3-O-acetyl-Xylp linkages in (2-O-MeGlcpA)3-O-acetyl-Xylp residues along with densely substituted and branched xylooligomers; activities that until now were missing from the arsenal of enzymes required for xylan conversion.

Original languageEnglish
Article number74
Number of pages12
JournalBiotechnology for Biofuels
Volume11
DOIs
Publication statusPublished - 22-Mar-2018
Externally publishedYes

Keywords

  • Acetyl xylan esterase
  • alpha-Glucuronidase
  • Glucuronic acid
  • Polysaccharide utilization loci
  • Xylan
  • SGNH hydrolase
  • CARBOHYDRATE ESTERASES
  • SGNH HYDROLASE
  • RHAMNOGALACTURONAN ACETYLESTERASE
  • ESCHERICHIA-COLI
  • THIOESTERASE-I
  • POLYSACCHARIDE
  • HEMICELLULOSES
  • FAMILY
  • CE16
  • OLIGOSACCHARIDES

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