# Structure and function of the monotopic phosphoglycosyl transferase superfamily: Initiators of biosynthesis of complex bacterial glycoconjugates

> **NIH GM R01** · BOSTON UNIVERSITY (CHARLES RIVER CAMPUS) · 2025 · $148,495

## Abstract

Complex glycoconjugates play a pivotal role in bacterial survival, colonization, and virulence, and
contribute to the interactions between symbiotic and pathogenic bacteria and their human hosts. Assembly
of these macromolecules is initiated on the cytoplasmic face of cell membranes, catalyzed by polyprenol
phosphate (PrenP) phosphoglycosyl transferases (PGTs). PGTs transfer a C1’-phosphosugar from a
soluble nucleoside diphosphate-sugar to a PrenP acceptor, yielding a membrane-bound polyprenol
diphosphosugar. Our studies focus on the exclusively prokaryotic PGT superfamily with a monotopic
membrane topology (monoPGTs). Our work has previously led to the mechanistic and structural
characterization of the monoPGTs, revealing a unique reentrant membrane helix supporting the structure
of the active-site residues and substrate-binding determinants. Identification of this core fold has enabled
bioinformatic analysis of sequences from diverse bacteria where the gene encoding the PGT enables
identification of the “signature step” in a dedicated set of genes that, together, describe the glycan of the
glycoconjugate product. The proposed studies will investigate the structures and binding landscapes of
the monoPGT superfamily, and the design of biological probes will establish the fundamental knowledge
and tools needed for validating and intervening in the action of potential therapeutic targets. In Aim 1,
sequence similarity networks will guide the choice of candidates for X-ray crystallographic analysis that
will be determined with detergent-solubilized protein in the small (Sm) monoPGTs, which encodes the core
fold without elaboration. Substrate and inhibitor-liganded structures and activity analysis will elucidate the
determinants of substrate specificity. Genome neighborhood networks will inform on the presence of genes
in the operon that catalyze the biosynthesis of unusual sugars to be tested as substrates. Aim 2 will address
the pathway regulation and flux assisted by

## Key facts

- **NIH application ID:** 11519325
- **Project number:** 7R01GM131627-08
- **Recipient organization:** BOSTON UNIVERSITY (CHARLES RIVER CAMPUS)
- **Principal Investigator:** Karen N. Allen
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** GM
- **Fiscal year:** 2025
- **Award amount:** $148,495
- **Award type:** 7
- **Project period:** 2019-02-01T00:00:00 → 2026-07-31T00:00:00

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11519325

## Citation

> US National Institutes of Health, RePORTER application 11519325, Structure and function of the monotopic phosphoglycosyl transferase superfamily: Initiators of biosynthesis of complex bacterial glycoconjugates (7R01GM131627-08). Retrieved via AI Analytics 2026-06-26 from https://api.ai-analytics.org/grant/nih/11519325. Licensed CC0.

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