Enzymatic Synthesis of Xylan Microparticles with Tunable\nMorphologies

Abstract

Xylans are a diverse\nfamily of hemicellulosic polysaccharides found\nin abundance within the cell walls of nearly all flowering plants.\nUnfortunately, naturally occurring xylans are highly heterogeneous,\nlimiting studies of their synthesis and structure–function\nrelationships. Here, we demonstrate that xylan synthase 1 from the\ncharophyte alga Klebsormidium flaccidum is a powerful biocatalytic tool for the bottom-up synthesis of pure\nβ-1,4 xylan polymers that self-assemble into microparticles\nin vitro. Using uridine diphosphate-xylose (UDP-xylose) and defined\nsaccharide primers as substrates, we demonstrate that the shape, composition,\nand properties of the self-assembling xylan microparticles could be\nreadily controlled via the fine structure of the xylan oligosaccharide\nprimer used to initiate polymer elongation. Furthermore, we highlight\ntwo approaches for bottom-up and surface functionalization of xylan\nmicroparticles with chemical probes and explore the susceptibility\nof xylan microparticles to enzymatic hydrolysis. Together, these results\nprovide a useful platform for structural and functional studies of\nxylans to investigate cell wall biosynthesis and polymer–polymer\ninteractions and suggest possible routes to new biobased materials\nwith favorable properties for biomedical and renewable applications.