The GH51 α-l-arabinofuranosidase from Paenibacillus sp. THS1 is multifunctional, hydrolyzing main-chain and side-chain glycosidic bonds in heteroxylans

Hanen Bouraoui (1, 2, 3, 4, 5) , Marie-Laure Desrousseaux (6) , Eleni Ioannou (7) , Pablo Alvira (7) , Mohamed Manaï (8) , Caroline Rémond (4) , Claire Dumon (7) , Narcis Fernandez-Fuentes (9, 10) , Michael O'Donohue (7)

1 Laboratoire des Ressources Sylvo-Pastorales
2 Institut Sylvo-Pastoral de Tabarka
3 UJ - Université de Jendouba
4 FARE - Fractionnement des AgroRessources et Environnement
5 URCA - Université de Reims Champagne-Ardenne
6 TWB - Toulouse White Biotechnology
7 LISBP - Laboratoire d'Ingénierie des Systèmes Biologiques et des Procédés
8 UBMB
9 Institute of Biological, Environmental, and Rural Sciences
10 Aberystwyth University

Background: Conceptually, multi functional enzymes are attractive because in the case of complex polymer hydrolysis having two or more activities defined by a single enzyme offers the possibility of synergy and reduced enzyme cocktail complexity. Nevertheless, multi functional enzymes are quite rare and are generally multi domain assemblies with each activity being defined by a separate protein module. However, a recent report described a GH51 arabinofuranosidase from Alicyclobacillus sp. A4 that displays both α l arabinofuranosidase and β d xylanase activities, which are defined by a single active site. Following on from this, we describe in detail another multi functional GH51 arabinofuranosidase and discuss the molecular basis of multifunctionality. Results: THSAbf is a GH51 α l arabinofuranosidase. Characterization revealed that THSAbf is active up to 75 °C, stable at 60 °C and active over a broad pH range (4–7). THSAbf preferentially releases para nitrophenyl from the l arabino furanoside ( k cat / K M = 1050 s − 1 mM − 1 ) and to some extent from d galactofuranoside and d xyloside. THSAbf is active on 4 O methylglucuronoxylans from birch and beechwood (10.8 and 14.4 U mg − 1 , respectively) and on sugar beet branched and linear arabinans (1.1 ± 0.24 and 1.8 ± 0.1 U mg − 1 ). Further investigation revealed that like the Alicyclo - bacillus sp. A4 α l arabinofuranosidase, THSAbf also displays endo xylanase activity, cleaving β 1,4 bonds in heteroxy lans. The optimum pH for THASAbf activity is substrate dependent, but ablation of the catalytic nucleophile caused a general loss of activity, indicating the involvement of a single active center. Combining the α l arabinofuranosidase with a GH11 endoxylanase did not procure synergy. The molecular modeling of THSAbf revealed a wide active site cleft and clues to explain multi functionality.

Domaines: Sciences du Vivant [q-bio]

Hanen Bouraoui, Marie-Laure Desrousseaux, Eleni Ioannou, Pablo Alvira, Mohamed Manaï, et al.. The GH51 α-l-arabinofuranosidase from Paenibacillus sp. THS1 is multifunctional, hydrolyzing main-chain and side-chain glycosidic bonds in heteroxylans. Biotechnology for Biofuels, 2016, 9 (1), pp.1-14. ⟨10.1186/s13068-016-0550-x⟩. ⟨hal-01595481⟩