The structural basis of fungal glucuronoyl esterase activity on natural substrates

Heidi A. Ernst, Caroline Mosbech, Annette E. Langkilde, Peter Westh, Anne S. Meyer, Jane Wittrup Agger*, Sine Larsen

*Corresponding author for this work

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Abstract

Structural and functional studies were conducted of the glucuronoyl esterase (GE) from Cerrena unicolor (CuGE), an enzyme catalyzing cleavage of lignin-carbohydrate ester bonds. CuGE is an α/β-hydrolase belonging to carbohydrate esterase family 15 (CE15). The enzyme is modular, comprised of a catalytic and a carbohydrate-binding domain. SAXS data show CuGE as an elongated rigid molecule where the two domains are connected by a rigid linker. Detailed structural information of the catalytic domain in its apo- and inactivated form and complexes with aldouronic acids reveal well-defined binding of the 4-O-methyl-a-D-glucuronoyl moiety, not influenced by the nature of the attached xylo-oligosaccharide. Structural and sequence comparisons within CE15 enzymes reveal two distinct structural subgroups. CuGE belongs to the group of fungal CE15-B enzymes with an open and flat substrate-binding site. The interactions between CuGE and its natural substrates are explained and rationalized by the structural results, microscale thermophoresis and isothermal calorimetry.
Original languageEnglish
Article number1026
JournalNature Communications
Volume11
Issue number1
Number of pages12
ISSN2041-1723
DOIs
Publication statusPublished - 2020

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