# Structural studies of virulence activation in Francisella tularensis

> **NIH NIH F31** · DUKE UNIVERSITY · 2020 · $39,302

## Abstract

PROJECT SUMMARY/ABSTRACT
The etiological agent of tularemia, Francisella tularensis, is one of the most infectious pathogens known and a
potential bioweapon. Francisella virulence stems from a gene cluster known as the Francisella pathogenicity
island (FPI) whose expression is under the control of a unique set of transcriptional regulators. MglA, SspA, and
PigR collaborate with the stress signal, guanosine tetraphosphate, or ppGpp, to activate transcription at the FPI.
However, the molecular mechanisms these factors use to drive virulence activation is unclear. In recent studies,
we have shown that MglA and SspA may be an integral subunit of Francisella RNA polymerase (RNAP), MglA
and SspA form a heterodimeric complex with an open cavity that binds ppGpp, and PigR, which has a predicted
winged helix-turn-helix motif and unstructured N- and C-termini, interacts with MglA-SspA in a ppGpp-dependent
manner. Based on this data, our central hypothesis is that virulence activation at the FPI occurs by a novel
mechanism where MglA-SspA is a subunit of RNAP and PigR bridges from (MglA-SspA)-ppGpp to DNA to
enhance transcription. The goal of this proposal is to uncover the mechanisms MglA-SspA uses to interact with
RNAP and PigR uses to bind DNA and (MglA-SspA)-ppGpp. This work will be accomplished through the
completion of two specific aims. First, I will solve a high-resolution (MglA-SspA)-PigR structure to aide in
structure-based drug design. In the second part of this aim, I will screen a small library of inhibitors identified via
in silico screening by Atomwise, Inc. For my second aim, I propose to utilize single-particle cryo-EM to solve
structures of multiple Francisella RNAP complexes. I will follow up on these structural studies with functional
assays to test our structure-based hypotheses. We expect that this work will lead to an understanding of the
mechanisms underlying virulence activation in this highly infectious pathogen and, importantly, our structures
will provide novel targets unique to Francisella to be used for rational drug design.
A significant part of my training plan is to gain expertise in X-ray crystallography and single-particle cryo-EM. I
propose to do this through coursework, training from my sponsor, Dr. Schumacher, and collaborator, Dr.
Bartesaghi, who are experts in these fields. I also explain how I will strengthen my background in microbiology,
learn to lead a research project, become an excellent mentor and collaborator, and improve upon my scientific
communication skills. The training plan will equip me with the knowledge and skills needed to complete the
proposed research and achieve my long-term goal of becoming an independent researcher in the field of
structural biology. This research will be conducted in the Schumacher laboratory as part of the Department of
Biochemistry at Duke University, which has a rich history of training remarkable investigators and will provide an
outstanding environment and resources that w...

## Key facts

- **NIH application ID:** 10066958
- **Project number:** 1F31AI150138-01A1
- **Recipient organization:** DUKE UNIVERSITY
- **Principal Investigator:** Brady A Travis
- **Activity code:** F31 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $39,302
- **Award type:** 1
- **Project period:** 2020-07-01 → 2023-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10066958

## Citation

> US National Institutes of Health, RePORTER application 10066958, Structural studies of virulence activation in Francisella tularensis (1F31AI150138-01A1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10066958. Licensed CC0.

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