Bacterial enzyme makes new type of biodegradable polymer

Date:
March 16, 2022
Source:
American Chemical Society
Summary:
Strings of sugars called polysaccharides are the most abundant
biopolymers on Earth. Because of their versatile and environmentally
friendly properties, these molecules could eventually replace some
plastics. Now, researchers have identified a previously unknown
bacterial enzyme that can make a new type of polysaccharide,
which is similar to the biopolymer chitin. The new molecule
is biodegradable and could be useful for drug delivery, tissue
engineering and other biomedical applications.



FULL STORY ========================================================================== Strings of sugars called polysaccharides are the most abundant biopolymers
on Earth. Because of their versatile and environmentally friendly
properties, these molecules could eventually replace some plastics. Now, researchers reporting in ACS Central Science have identified a previously unknown bacterial enzyme that can make a new type of polysaccharide, which
is similar to the biopolymer chitin. The new molecule is biodegradable
and could be useful for drug delivery, tissue engineering and other
biomedical applications.


========================================================================== Polysaccharides play many roles in organisms, and 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. Stephen Withers and 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, the researchers
identified a glycoside phosphorylase enzyme from bacteria called
Acholeplasma laidlawii, a common contaminant of laboratory cell
cultures. The team expressed and purified the enzyme, discovering that
it could synthesize a new type of polysaccharide, which they 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
team determined the crystal structure of the glycoside phosphorylase,
which they suspect could be involved in maintenance of A. laidlawii's
cellular membrane.

As such, researchers 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, the researchers say.

The authors acknowledge funding and support from the Natural Sciences
and Engineering Research Council of Canada, the Canadian Institutes
for Health Research, the U.S. Department of Energy, the Howard Hughes
Medical Institute and the National Institutes of Health.


========================================================================== Story Source: Materials provided by American_Chemical_Society. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Spencer S. Macdonald, Jose H. Pereira, Feng Liu, Gregor Tegl, Andy
DeGiovanni, Jacob F. Wardman, Samuel Deutsch, Yasuo Yoshikuni,
Paul D.

Adams, Stephen G. Withers. A Synthetic Gene Library Yields a
Previously Unknown Glycoside Phosphorylase That Degrades and
Assembles Poly-b-1,3- GlcNAc, Completing the Suite of b-Linked
GlcNAc Polysaccharides. ACS Central Science, 2022; DOI:
10.1021/acscentsci.1c01570 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220316091756.htm

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