Carbohydrate binding module of family 48 enable ferulic acid esterases action on polymeric arabinoxylan

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Abstract

Arabinoxylans (AXs) are a major component of hemicelluloses, which is widely distributed in secondary cell walls of plants. Their backbone is composed of β-1,4-linked xylopyranose residues that are single substituted with α-L-1,3-arabinofuranose (Araf) or double substituted with both α-L-1,2- and α-L-1,3-Araf, which can be further substituted with by 5-O-ferulic acid and other hydroxycinnamic acids [1]. Ferulic acid esterases (FAEs) catalyze the hydrolysis of ester bonds between hydroxycinnamic acids and Araf, however, most characterized FAEs do not display a preference for polymeric substrates [2,3]. Recently, a number of carbohydrate esterase family 1 (CE1) identified in metagenomic studies was shown to have a carbohydrate binding module of family 48 (CBM48) appended [4,5], a family associated with starch binding [6]. Our phylogenetic analysis demonstrated that these are in fact CBM48s suggesting that CBM48s is a polyspecific family since CE1s do not target starch. Adsorption assays with two CE1-CBM48 enzymes demonstrated binding to AXs, but not to starch, which was supported by a surface plasmon resonance analysis showing no binding to β-cyclodextrin or maltohexaose. Binding was detected to arabino- and xylooligosaccharides and interestingly also to maltotetraose. The two CE1-CBM48 enzymes released FA from AXs, while the CE1 domain on its own only released FA from oligosaccharides and unlike the full-length enzymes the CE1 domain was unable to bind to AXs. Crystal structures of the two CE1-CBM48s revealed two integrally folded units and multiple structurally conserved hydrogen bonds fix the CBM48’s position relative to the CE1 domains. Molecular dynamics simulations confirmed that the two domains form a rigid structure. Docking studies suggest that the xylan main chain is accommodated in the cleft formed at the interface between the CE1 and CBM48 domains.
Original languageEnglish
Publication date2019
Number of pages1
Publication statusPublished - 2019
Event13th Carbohydrate Bioengineering Meeting - Université Paul Sabatier, Toulouse, France
Duration: 19 May 201922 May 2019
Conference number: 13
https://cbm13.sciencesconf.org/

Conference

Conference13th Carbohydrate Bioengineering Meeting
Number13
LocationUniversité Paul Sabatier
CountryFrance
CityToulouse
Period19/05/201922/05/2019
Internet address

Cite this

Wilkens, C. (2019). Carbohydrate binding module of family 48 enable ferulic acid esterases action on polymeric arabinoxylan. Poster session presented at 13th Carbohydrate Bioengineering Meeting, Toulouse, France.