7TOH

Crystal structure of carbohydrate esterase PbeAcXE, in complex with MeGlcpA-Xylp

Summary for 7TOH

• Entry DOI: 10.2210/pdb7toh/pdb
• Descriptor: SGNH hydrolase, 4-O-methyl-alpha-D-glucopyranuronic acid-(1-2)-beta-D-xylopyranose (3 entities in total)
• Functional Keywords: carbohydrate esterase, ce, acetyl xylan esterases, xylan esterase, acxe, hydrolase
• Biological source: Prolixibacter bellariivorans
• Total number of polymer chains: 1
• Total formula weight: 43070.25

Authors

Stogios, P.J.,Skarina, T.,Di Leo, R.,Jurak, E.,Master, E. (deposition date: 2022-01-24, release date: 2022-04-13, Last modification date: 2024-10-30)

Primary citation

Penttinen, L.,Kouhi, V.,Faure, R.,Skarina, T.,Stogios, P.,Master, E.,Jurak, E.
Elucidating Sequence and Structural Determinants of Carbohydrate Esterases for Complete Deacetylation of Substituted Xylans.
Molecules, 27:-, 2022

PubMed Abstract: 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 (Xyl) backbone that can be substituted with an acetyl group at -2 and 3 positions, and α-(1→2)-linked 4--methylglucopyranosyluronic acid (MeGlcA). Acetyl xylan esterases (AcXE) that target mono- or doubly acetylated Xyl are well characterized; however, the previously studied AcXE from (AcXE) was the first to remove the acetyl group from 2--MeGlcA-3--acetyl-substituted Xyl units, yet structural characteristics of these enzymes remain unspecified. Here, six homologs of AcXE were produced and three crystal structures of the enzymes were solved. Two of them are complex structures, one with bound MeGlcA and another with acetate. All homologs were confirmed to release acetate from 2--MeGlcA-3--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 AcXE 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 MeGlcA-Xyl ligand is directed by positively charged and highly conserved residues at the interface of the CBM and SGNH domains of the enzyme.

PubMed: 35566004
DOI: 10.3390/molecules27092655

Experimental method

X-RAY DIFFRACTION (1.26 Å)