Development of Rare Bacterial Monosaccharide Analogs for Metabolic Glycan Labeling in Pathogenic Bacteria

Abstract

Bacterial glycans contain rare, exclusively bacterial monosaccharides that are frequently linked to pathogenesis and essentially absent from human cells. Therefore, bacterial glycans are intriguing molecular targets. However, systematic discovery of bacterial glycoproteins is hampered by the presence of rare deoxy amino sugars, which are refractory to traditional glycan-binding reagents. Thus, the development of chemical tools that label bacterial glycans is a crucial step toward discovering and targeting these biomolecules. Here we explore the extent to which metabolic glycan labeling facilitates the studying and targeting of glycoproteins in a range of pathogenic and symbiotic bacterial strains. We began with an azide-containing analog of the naturally abundant monosaccharide N-acetylglucosamine and discovered that it is not broadly incorporated into bacterial glycans, thus revealing a need for additional azidosugar substrates to broaden the utility of metabolic glycan labeling in bacteria. Therefore, we designed and synthesized analogs of the rare deoxy amino d-sugars N-acetylfucosamine, bacillosamine, and 2,4-diacetamido-2,4,6-trideoxygalactose and established that these analogs are differentially incorporated into glycan-containing structures in a range of pathogenic and symbiotic bacterial species. Further application of these analogs will refine our knowledge of the glycan repertoire in diverse bacteria and may find utility in treating a variety of infectious diseases with selectivity.

Chemical Reporters for Exploring Microbiology and Microbiota Mechanisms

“…[67] In contrast, FucNAz was not incorporated into anyo ft hese bacteria ( Figure 9D). [67] Chemical reporterso f other bacterial glycanss uch as pseudaminic acid by the Ta nner [68] and Li [69] laboratories ( Figure 9E)a sw ell as bacteriaspecific UDP monosaccharides by the Imperiali laboratory [70] have also been developedf or labeling proteins in different bacterials pecies. These specific bacteria-specific monosaccharide reportersa nd others should providen ew tools to selectively label distinct species, characterize biosynthetic enzymes and discover bacterial glycoproteins.…”

“…Although protein glycosylation in bacteria shares similar biosynthetic machinery to eukaryotes, the bacteria glycans have unique and diverse structures (Figure A) . To label these bacterial glycoproteins, the Dube laboratory synthesized several azido‐monosaccharides and explored their metabolic incorporation in diverse bacterial species (Figure B–D) . For example, GlcNAz can only label proteins in Helicobacter pylori and Ralstonia solanacerum (Figure B), while azide analogues of bacillosamine (Bac‐diNAz) and 2,4‐diacetamido‐2,4,6‐trideoxygalactose (DATDG‐diNAz) label proteins in H. pylori , Campylobacter jejuni , Burkholderia thailandensis and R. solanacerum (Figure C) .…”

“…A) Structures of representative bacterial protein glycosylations. B) Ac 4 GlcNAz and Ac 3 ‐6‐az‐GlcNAc . C) Ac 2 ‐Bac‐diNAz and Ac 2 ‐DATDG‐diNAz .…”

“…C) Ac 2 ‐Bac‐diNAz and Ac 2 ‐DATDG‐diNAz . D) Ac 3 FucNAz . E) Pseudaminic acid reporters Ac 2 ‐Alt‐4NAz and Ac 2 ‐Alt‐2NAz …”

“…[67] D) Ac 3 FucNAz. [67] E) Pseudaminic acid reporters Ac 2 -Alt-4NAza nd Ac 2 -Alt-2NAz. [68,69] ChemBioChem 2020, 21,[19][20][21][22][23][24][25][26][27][28][29][30][31][32] www.chembiochem.org in Clostridium difficile for lipoprotein biogenesis.…”