Scientists Create New Type of Biodegradable Polymeric Material

A team of researchers from the University of British Columbia and elsewhere has identified a bacterial enzyme that can make a new type of polysaccharide, which is similar to the biopolymer chitin. Named acholetin, the new polymer is biodegradable and could be useful for drug delivery, tissue engineering and other applications.

Use of the reverse phosphorolysis action of acholetin phosphorylase (AchP) provides an efficient method to enzymatically synthesize acholetin, which is a new biodegradable polymeric material. Image credit: Macdonald et al., doi: 10.1021/acscentsci.1c01570.

Strings of sugars called polysaccharides are the most abundant biopolymers on Earth and play many roles in organisms.

Because they are biocompatible and biodegradable, these molecules are promising carrier materials for a broad range of therapeutics.

The identity of individual sugar molecules in the chain, and the way they are linked together, make them function in different ways.

Enzymes known as glycoside phosphorylases can cut certain polysaccharides apart or make new ones, depending on the reaction conditions.

For example, one such enzyme makes chitin, the major component of arthropod exoskeletons and fungal cell walls.

University of British Columbia’s Dr. Stephen Withers and his colleagues wondered if there might be previously unknown, naturally occurring enzymes that could make new types of polysaccharides.

Using genomic data and activity-based screening, they identified a glycoside phosphorylase enzyme from a species of bacterium called Acholeplasma laidlawii.

They expressed and purified the enzyme, discovering that it could synthesize a new type of polysaccharide.

Named acholetin, the new biopolymer is similar in composition to chitin and to a biofilm-forming polysaccharide, but its sugar molecules are linked together in way that differs from these known biopolymers.

The researchers also determined the crystal structure of the glycoside phosphorylase, which they suspect could be involved in maintenance of Acholeplasma laidlawii’s cellular membrane.

As such, they might be able to target the enzyme to prevent cell culture contamination with the bacteria, in addition to using the enzyme to make the new biopolymer.

“Acholetin has wide-ranging potential as a new type of biocompatible, biodegradable material,” they said.

Their paper appears in the journal ACS Central Science.

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Spencer S. Macdonald et al. A Synthetic Gene Library Yields a Previously Unknown Glycoside Phosphorylase That Degrades and Assembles Poly-β-1,3-GlcNAc, Completing the Suite of β-Linked GlcNAc Polysaccharides. ACS Cent. Sci, published online March 16, 2022; doi: 10.1021/acscentsci.1c01570