9EGA

Crystal Structure of a CE20 carbohydrate acetylesterase from Pedobacter psychrotolerans (PpCE20_II), with ancillary domain

Summary for 9EGA

• Entry DOI: 10.2210/pdb9ega/pdb
• Related: 9H4U
• Descriptor: Sialate O-acetylesterase, TRIETHYLENE GLYCOL, MAGNESIUM ION, ... (5 entities in total)
• Functional Keywords: esterase, carbohydrate, polysaccharide, multimodular, hydrolase
• Biological source: Pedobacter psychrotolerans; More
• Total number of polymer chains: 2
• Total formula weight: 145804.86

Authors

Vieira, P.S.,Morais, M.A.B.,Murakami, M.T. (deposition date: 2024-11-21, release date: 2025-08-13)

Primary citation

Teune, M.,Vieira, P.S.,Dohler, T.,Palm, G.J.,Dutschei, T.,Bartosik, D.,Berndt, L.,Persinoti, G.F.,Maass, S.,Becher, D.,Schweder, T.,Murakami, M.T.,Lammers, M.,Bornscheuer, U.T.
Insights into a water-mediated catalytic triad architecture in CE20 carbohydrate esterases.
Nat Commun, 16:7034-7034, 2025

PubMed Abstract: Carbohydrate esterases modify polysaccharides by removing different ester moieties thereby affecting their physicochemical properties and their accessibility by glycoside hydrolases. We determined the full-length structures of two members (Fl8CE20_II and PpCE20_II) from the carbohydrate esterase family 20 (CE20) by X-ray crystallography that feature an ancillary domain, inserted into the catalytic SGNH-hydrolase domain. Detailed structural analysis identifies a so far undescribed catalytic triad architecture which lacks the typical aspartate for polarization of the histidine but instead reveals a precisely coordinated water molecule mediating contact between the His and Asp. This coordinated water in the Ser-His-(HO-Asp/Asn) motif, as further confirmed by mutational studies and by determination of kinetic constants, is crucial for catalytic activity. We therefore term this active site architecture a water-mediated catalytic triad.

PubMed: 40745183
DOI: 10.1038/s41467-025-62387-5

Experimental method

X-RAY DIFFRACTION (1.35 Å)