# Branched Chain Amino Acid Metabolism During Anthrax

> **NIH NIH R21** · BAYLOR COLLEGE OF MEDICINE · 2020 · $200,000

## Abstract

Project Summary
Branched amino acids (valine, leucine, and isoleucine) are essential for life. Some organisms,
like humans, acquire these amino acids from their diet and thus lack the ability to make them.
Others, like plants, harbor the full biosynthetic machinery for their production and do so when
nutrients are scarce. Some pathogenic bacteria seemingly do both; they have production
capacity but also possess transporters that mediate their uptake from the environment.
However, it is unclear which of these two arms, acquisition versus synthesis, is most important
during infection of their vertebrate hosts. In this project, we employ the use of B. anthracis, the
causative agent of anthrax disease whose prolific replication in blood and tissues makes it ideal
for studying nutrient uptake, to determine the importance of branched amino acid metabolism to
the multi-stage infectious process of this pathogen. Working under the premise that bacilli needs
to liberate branched amino acids from the breakdown of blood proteins to sustain high levels of
growth, we hypothesize that the transport of freed branched amino acids in serum is necessary
for anthrax disease. In Aim 1, we use isogenic mutant strains deficient in each arm (transport
versus synthesis) of branched amino acid metabolism to determine their overall contribution to
pulmonary anthrax, the most lethal type. In Aim 2, we explore the exact role of these two arms
to each stage in the infectious cycle of bacilli, including outgrowth inside infected macrophages
and rapid expansion of vegetative bacilli in blood and blood-like environments. This work takes
the first step towards knowing if branched amino acid production and/or transport represents a
viable entry point for new antimicrobial strategies.

## Key facts

- **NIH application ID:** 9936353
- **Project number:** 5R21AI146481-02
- **Recipient organization:** BAYLOR COLLEGE OF MEDICINE
- **Principal Investigator:** ANTHONY W MARESSO
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $200,000
- **Award type:** 5
- **Project period:** 2019-06-01 → 2022-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9936353

## Citation

> US National Institutes of Health, RePORTER application 9936353, Branched Chain Amino Acid Metabolism During Anthrax (5R21AI146481-02). Retrieved via AI Analytics 2026-05-28 from https://api.ai-analytics.org/grant/nih/9936353. Licensed CC0.

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