| Title: |
The xyl-doc gene cluster of Ruminiclostridium cellulolyticum encodes GH43- and GH62-α-l-arabinofuranosidases with complementary modes of action. |
| Authors: |
Mroueh, M.; Aruanno, M.; Borne, R.; de Philip, P.; Fierobe, H.P.; Tardif, C.; Pagès, S. |
| Publication Year: |
2019 |
| Collection: |
Université de Lausanne (UNIL): Serval - Serveur académique lausannois |
| Subject Terms: |
Arabinoxylan; Biomass degradation; Cellulosomes; Characterization of enzymes; Ruminiclostridium cellulolyticum; Substrate specificity; α-l-Arabinofuranosidase |
| Description: |
The α-l-arabinofuranosidases (α-l-ABFs) are exoenzymes involved in the hydrolysis of α-l-arabinosyl linkages in plant cell wall polysaccharides. They play a crucial role in the degradation of arabinoxylan and arabinan and they are used in many biotechnological applications. Analysis of the genome of R. cellulolyticum showed that putative cellulosomal α-l-ABFs are exclusively encoded by the xyl-doc gene cluster, a large 32-kb gene cluster. Indeed, among the 14 Xyl-Doc enzymes encoded by this gene cluster, 6 are predicted to be α-l-ABFs belonging to the CAZyme families GH43 and GH62. The biochemical characterization of these six Xyl-Doc enzymes revealed that four of them are α-l-ABFs. GH43 16 -1229 (RcAbf43A) which belongs to the subfamily 16 of the GH43, encoded by the gene at locus Ccel_1229, has a low specific activity on natural substrates and can cleave off arabinose decorations located at arabinoxylan chain extremities. GH43 10 -1233 (RcAbf43A d2,3 ), the product of the gene at locus Ccel_1233, belonging to subfamily 10 of the GH43, can convert the double arabinose decorations present on arabinoxylan into single O2- or O3-linked decorations with high velocity (k cat = 16.6 ± 0.6 s -1 ). This enzyme acts in synergy with GH62-1234 (RcAbf62A m2,3 ), the product of the gene at locus Ccel_1234, a GH62 α-l-ABF which hydrolyzes α-(1 → 3) or α-(1 → 2)-arabinosyl linkages present on polysaccharides and arabinoxylooligosaccharides monodecorated. Finally, a bifunctional enzyme, GH62-CE6-1240 (RcAbf62B m2,3 Axe6), encoded by the gene at locus Ccel_1240, which contains a GH62-α-l-ABF module and a carbohydrate esterase (CE6) module, catalyzes deacylation of plant cell wall polymers and cleavage of arabinosyl mono-substitutions. These enzymes are also active on arabinan, a component of the type I rhamnogalacturonan, showing their involvement in pectin degradation. Arabinofuranosyl decorations on arabinoxylan and pectin strongly inhibit the action of xylan-degrading enzymes and pectinases. α-l-ABFs encoded by the xyl-doc ... |
| Document Type: |
article in journal/newspaper |
| File Description: |
application/pdf |
| Language: |
English |
| ISBN: |
978-0-00-470983-3; 0-00-470983-7 |
| ISSN: |
1754-6834 |
| Relation: |
Biotechnology for Biofuels; https://iris.unil.ch/handle/iris/44562; serval:BIB_0A67B4908CA9; 000470983700001 |
| DOI: |
10.1186/s13068-019-1483-y |
| Availability: |
https://iris.unil.ch/handle/iris/44562; https://doi.org/10.1186/s13068-019-1483-y |
| Accession Number: |
edsbas.667330F2 |
| Database: |
BASE |