6sxs | pdb_00006sxs
GH54 a-l-arabinofuranosidase soaked with cyclic sulfate inhibitor
Structural highlights
FunctionABFB_ASPKW Alpha-L-arabinofuranosidase involved in the degradation of arabinoxylan, a major component of plant hemicellulose. Able to hydrolyze 1,5-, 1,3- and 1,2-alpha-linkages not only in L-arabinofuranosyl oligosaccharides, but also in polysaccharides containing terminal non-reducing L-arabinofuranoses in side chains, like L-arabinan, arabinogalactan and arabinoxylan.[1] [2] Publication Abstract from PubMedIdentifying and characterizing the enzymes responsible for an observed activity within a complex eukaryotic catabolic system remains one of the most significant challenges in the study of biomass-degrading systems. The debranching of both complex hemicellulosic and pectinaceous polysaccharides requires the production of alpha-L-arabinofuranosidases among a wide variety of co-expressed carbohydrate-active enzymes. To selectively detect and identify alpha-L-arabinofuranosidases produced by fungi grown on complex biomass, potential covalent inhibitors and probes which mimic alpha-L-arabinofuranosides were sought. The conformational free energy landscapes of free alpha-L-arabinofuranose and several rationally designed covalent alpha-L-arabinofuranosidase inhibitors were analyzed. A synthetic route to these inhibitors was subsequently developed based on a key Wittig-Still rearrangement. Through a combination of kinetic measurements, intact mass spectrometry, and structural experiments, the designed inhibitors were shown to efficiently label the catalytic nucleophiles of retaining GH51 and GH54 alpha-L-arabinofuranosidases. Activity-based probes elaborated from an inhibitor with an aziridine warhead were applied to the identification and characterization of alpha-L-arabinofuranosidases within the secretome of A. niger grown on arabinan. This method was extended to the detection and identification of alpha-L-arabinofuranosidases produced by eight biomass-degrading basidiomycete fungi grown on complex biomass. The broad applicability of the cyclophellitol-derived activity-based probes and inhibitors presented here make them a valuable new tool in the characterization of complex eukaryotic carbohydrate-degrading systems and in the high-throughput discovery of alpha-L-arabinofuranosidases. Rational Design of Mechanism-Based Inhibitors and Activity-Based Probes for the Identification of Retaining alpha-L-Arabinofuranosidases.,McGregor N, Artola M, Nin-Hill A, Linzel D, Haon M, Reijngoud J, Ram AFJ, Rosso MN, van der Marel GA, Codee JDC, van Wezel GP, Berrin JG, Rovira C, Overkleeft HS, Davies GJ J Am Chem Soc. 2020 Feb 13. doi: 10.1021/jacs.9b11351. PMID:32053363[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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