# Deciphering fundamental biological processes involving protein-nucleic acid interactions at the molecular level

> **NIH NIH R35** · DUKE UNIVERSITY · 2024 · $239,000

## Abstract

ABSTRACT
The central goal of the Schumacher laboratory is to deduce principles governing fundamental biological
processes involving protein-nucleic acid interactions and their regulation, with a particular focus on processes
important in microbial pathogenesis. While we aim to elucidate these mechanisms at the atomic level, it is
critical that we are able to place our molecular findings within a biologically relevant context. Importantly, the
elucidation of such physiologically relevant mechanisms also provides molecular targets for the development of
antimicrobial agents, which are urgently needed; recent estimates suggest that deaths from antimicrobial
resistance (AMR) bacteria may exceed 10 million deaths worldwide by 2050 if steps are not taken to generate
new treatments. Microbes must be able to sense and respond to environmental changes for their survival and
in some cases, proper development. Hence, our studies focus on essential processes in which environmental
cues are signaled and detected. Recent studies have shown that the metabolic state of bacteria influences
their susceptibility to antibiotics and that antibiotic efficacy can be enhanced by altering the metabolic state of
bacteria. A main area of interest in the lab has been elucidating the mechanisms by which essential elements,
such as nitrogen, are sensed and regulated in microbes. The central enzyme in nitrogen homeostasis is
glutamine synthetase (GS), which catalyzes the assimilation of ammonium ions into glutamine, and thus
serves as the major nitrogen donor for the generation of all key metabolites. Using a combination of cryo-EM,
X-ray crystallography, biochemistry and in vivo studies, we have dissected the GS-GlnR signaling pathway in
bacteria and uncovered a novel mechanism of dual regulation involving altered oligomerization of both
proteins. We term this form of regulation, “oligomer modulation”. We have gone on to show that oligomer
modulation may, in fact, be a commonly used mode of GS regulation. Specifically, we found that the
Methanosarcina mazei (Mm) GS, which forms a large dodecameric machine at high concentrations, is present
as inactive dimers at physiologically relevant concentrations. This mechanism was suggested by our structural
studies, which were performed at high concentrations. However, mass photometry (MP) permitted an analysis
of the GS oligomer state at physiological levels. This study thus shows the power of MP in placing our
structural findings within a biological framework. MP could be utilized in all our studies to assess complexes
and oligomers and as a result to aid in the development of biologically relevant macromolecular models that
can be targeted for drug development.

## Key facts

- **NIH application ID:** 11031609
- **Project number:** 3R35GM130290-07S1
- **Recipient organization:** DUKE UNIVERSITY
- **Principal Investigator:** Maria Schumacher
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $239,000
- **Award type:** 3
- **Project period:** 2019-01-01 → 2027-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11031609

## Citation

> US National Institutes of Health, RePORTER application 11031609, Deciphering fundamental biological processes involving protein-nucleic acid interactions at the molecular level (3R35GM130290-07S1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/11031609. Licensed CC0.

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