# Mechanistic characterization and regulation of the non-redundant phu and has heme uptake systems of Pseudomonas aeruginosa

> **NIH NIH R01** · UNIVERSITY OF MARYLAND BALTIMORE · 2021 · $383,301

## Abstract

Pathogenic bacteria require iron for their survival and virulence. The opportunistic pathogen Pseudomonas
aeruginosa has multiple mechanisms by which it can acquire iron, including ferric and ferrous iron uptake
systems. However, within the host P. aeruginosa can adapt to utilize heme via the heme assimilation (has) and
Pseudomonas heme utilization (phu) systems. We have recently shown the OM receptor PhuR has a unique
His-Tyr coordination, which is an emerging motif in high affinity heme acquisition systems. 13C-heme isotopic
labeling studies combined with bacterial genetics suggest the PhuR receptor is the high capacity uptake
receptor, with the HasR receptor acting primarily as a sensor and regulator of heme utilization. Furthermore,
we have shown the heme metabolite biliverdin IXβ is a feedback regulator of the heme sensing system (has),
as well as several virulence mechanisms including the pyochelin and Zn/Ni-pseudopaline uptake system, Type
III secretion systems (ExoS and ExoT), and extracellular proteases (LasB). The goal of the proposal is to
understand the regulation and molecular mechanism of heme acquisition in P. aeruginosa. Specifically, we will
elucidate the heme-dependent regulatory elements controlling expression of the has system through
transcriptional and translational fusion studies. Targeted transcriptional and post-transcriptional studies will be
complimented by global analysis through transcriptomic and and proteomic analyses. We will further define
the substrate specificity of the bis-His HasR and His-Tyr coordinated PhuR and their respective contributions to
heme acquisition and regulation. Contributions of the Has and Phu systems to heme acquisition and virulence
within the host will be tested in murine acute and chronic lung infection models. In addition, dual RNA-seq will
be performed to simultaneously determine the P. aeruginosa and murine host response to infection. MALDI-
MSI will be used in combination with quantitative LC-MS methods to determine the spatial distribution heme
metabolites (BVIX isomers) and host-pathogen biomarkers in PAO1 and heme utilization mutants. Completion
of the studies will provide a molecular basis for P. aeruginosa adaption to heme utilization in the context of the
host-pathogen interaction.

## Key facts

- **NIH application ID:** 10148631
- **Project number:** 5R01AI134886-04
- **Recipient organization:** UNIVERSITY OF MARYLAND BALTIMORE
- **Principal Investigator:** Angela Wilks
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $383,301
- **Award type:** 5
- **Project period:** 2018-05-01 → 2023-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10148631

## Citation

> US National Institutes of Health, RePORTER application 10148631, Mechanistic characterization and regulation of the non-redundant phu and has heme uptake systems of Pseudomonas aeruginosa (5R01AI134886-04). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10148631. Licensed CC0.

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