Elucidating Sequence and Structural Determinants of Carbohydrate Esterases for Complete Deacetylation of Substituted Xylans

Leena Penttinen, Vera Kouhi, Régis Fauré, Tatiana Skarina, Peter Stogios, Emma Master, Edita Jurak*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

3 Citations (Scopus)
72 Downloads (Pure)


Acetylated glucuronoxylan is one of the most common types of hemicellulose in nature. The structure is formed by a β-(1→4)-linked D-xylopyranosyl (Xylp) backbone that can be substituted with an acetyl group at O-2 and O-3 positions, and α-(1→2)-linked 4-O-methylglucopyranosyluronic acid (MeGlcpA). Acetyl xylan esterases (AcXE) that target mono-or doubly acetylated Xylp are well characterized; however, the previously studied AcXE from Flavobacterium johnsoniae (FjoAcXE) was the first to remove the acetyl group from 2-O-MeGlcpA-3-O-acetyl-substituted Xylp units, yet structural characteristics of these enzymes remain unspecified. Here, six homologs of FjoAcXE were produced and three crystal structures of the enzymes were solved. Two of them are complex structures, one with bound MeGlcpA and another with acetate. All homologs were confirmed to release acetate from 2-O-MeGlcpA-3-O-acetyl-substituted xylan, and the crystal structures point to key structural elements that might serve as defining features of this unclassified carbohydrate esterase family. Enzymes comprised two domains: N-terminal CBM domain and a C-terminal SGNH domain. In FjoAcXE and all studied homologs, the sequence motif around the catalytic serine is Gly-Asn-Ser-Ile (GNSI), which differs from other SGNH hydrolases. Binding by the MeGlcpA-Xylp ligand is directed by positively charged and highly conserved residues at the interface of the CBM and SGNH domains of the enzyme.

Original languageEnglish
Article number2655
Number of pages15
Issue number9
Early online date20 Apr 2022
Publication statusPublished - 1 May 2022
MoE publication typeA1 Journal article-refereed


  • acetyl xylan esterase
  • carbohydrate esterase
  • SGNH hydrolase
  • xylan


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