# Biochemical Investigations of Sugar-Modifying Enzymes

> **NIH NIH R35** · UNIVERSITY OF WISCONSIN-MADISON · 2020 · $437,349

## Abstract

PROJECT SUMMARY/ABSTRACT
 Bacteria produce an astonishingly diverse array of carbohydrate-based macromolecules that serve
important physiological roles. The lipopolysaccharide or LPS, for example, is a complex glycoconjugate
attached to the outer membranes of Gram-negative bacteria. Conceptually, the LPS can be thought of in
terms of three regions: the lipid A component, the core oligosaccharide, and the O-antigen. It is the O-antigen
that displays the most variation from species to species and that, in addition to the lipid A moiety, plays a role
in virulence.
 Likewise, the capsular polysaccharides, which surround both pathogenic Gram-positive and Gram-
negative bacteria, serve as the first lines of defense against the host immune system. These high molecular
weight polysaccharides function by camouflaging cell surface components that would normally elicit the
immune response. Often the sugars in the capsular polysaccharides are modified by the attachment of a
variety of moieties including an O-methyl phosphoramidate group, which has been shown to be involved in
host invasion and bacteriophage recognition. In addition, some capsular polysaccharides contain nonulosonic
acids, nine-carbon based monosaccharides that have been implicated in virulence.
 The intellectual goals of this MIRA award are threefold: (1) to expand upon our current knowledge of the
structures and activities of the enzymes involved in the biosynthesis of O-antigen sugars, (2) to provide a
molecular framework for understanding the biosynthesis of the O-methyl phosphoramidate group in
Campylobacter jejuni, and (3) to explore the structures and functions of the enzymes involved in the
biosyntheses of nonulosonic acids from Acinetobacter baumannii, an organism that has been placed into the
“Critical” category by the World Health Organization for the development of new antibiotics.
 Techniques to be utilized include X-ray crystallography, site-directed mutagenesis, and kinetic analyses.
Importantly, preliminary data for many of the proposed investigations are already available.
 Our studies have and will continue to inform research into bacterial pathogenicity. Given that the LPS and
capsular polysaccharides play critical roles in bacterial virulence, the enzymes to be investigated may
ultimately serve as targets for antimicrobial drug design.

## Key facts

- **NIH application ID:** 9840295
- **Project number:** 1R35GM134643-01
- **Recipient organization:** UNIVERSITY OF WISCONSIN-MADISON
- **Principal Investigator:** Hazel M. Holden
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $437,349
- **Award type:** 1
- **Project period:** 2020-02-01 → 2025-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9840295

## Citation

> US National Institutes of Health, RePORTER application 9840295, Biochemical Investigations of Sugar-Modifying Enzymes (1R35GM134643-01). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/9840295. Licensed CC0.

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