6RZN

Crystal structure of the N-terminal carbohydrate binding module family 48 and ferulic acid esterase from the multi-enzyme CE1-GH62-GH10

Summary for 6RZN

• Entry DOI: 10.2210/pdb6rzn/pdb
• Descriptor: Ferulic acid esterase (2 entities in total)
• Functional Keywords: ferulic acid esterease, carbohydrate esterase family 1, ce1, cbm48, carbohydrate binding module family 48, hydrolase
• Biological source: uncultured bacterium
• Total number of polymer chains: 2
• Total formula weight: 85574.62

Authors

Fredslund, F.,Welner, D.H.,Wilkens, C. (deposition date: 2019-06-13, release date: 2019-09-25, Last modification date: 2024-01-24)

Primary citation

Holck, J.,Fredslund, F.,Moller, M.S.,Brask, J.,Krogh, K.B.R.M.,Lange, L.,Welner, D.H.,Svensson, B.,Meyer, A.S.,Wilkens, C.
A carbohydrate-binding family 48 module enables feruloyl esterase action on polymeric arabinoxylan.
J.Biol.Chem., 294:17339-17353, 2019

PubMed Abstract: Feruloyl esterases (EC 3.1.1.73), belonging to carbohydrate esterase family 1 (CE1), hydrolyze ester bonds between ferulic acid (FA) and arabinose moieties in arabinoxylans. Recently, some CE1 enzymes identified in metagenomics studies have been predicted to contain a family 48 carbohydrate-binding module (CBM48), a CBM family associated with starch binding. Two of these CE1s, wastewater treatment sludge (wts) Fae1A and wtsFae1B isolated from wastewater treatment surplus sludge, have a cognate CBM48 domain and are feruloyl esterases, and wtsFae1A binds arabinoxylan. Here, we show that wtsFae1B also binds to arabinoxylan and that neither binds starch. Surface plasmon resonance analysis revealed that wtsFae1B's for xylohexaose is 14.8 μm and that it does not bind to starch mimics, β-cyclodextrin, or maltohexaose. Interestingly, in the absence of CBM48 domains, the CE1 regions from wtsFae1A and wtsFae1B did not bind arabinoxylan and were also unable to catalyze FA release from arabinoxylan. Pretreatment with a β-d-1,4-xylanase did enable CE1 domain-mediated FA release from arabinoxylan in the absence of CBM48, indicating that CBM48 is essential for the CE1 activity on the polysaccharide. Crystal structures of wtsFae1A (at 1.63 Å resolution) and wtsFae1B (1.98 Å) revealed that both are folded proteins comprising structurally-conserved hydrogen bonds that lock the CBM48 position relative to that of the CE1 domain. wtsFae1A docking indicated that both enzymes accommodate the arabinoxylan backbone in a cleft at the CE1-CBM48 domain interface. Binding at this cleft appears to enable CE1 activities on polymeric arabinoxylan, illustrating an unexpected and crucial role of CBM48 domains for accommodating arabinoxylan.

PubMed: 31558605
DOI: 10.1074/jbc.RA119.009523

Experimental method

X-RAY DIFFRACTION (1.907 Å)