Biology subjects

Beg, A. Z.

Publications and source records attributed to Beg, A. Z..

3 recordsLinked to original sources

bioRxiv2026

T6SS mutants exploit itaconate to support infection of phagocytes

Pseudomonas aeruginosa is a major cause of persistent pneumonias that are not readily cleared by seemingly appropriate antimicrobial therapy. We identified a reservoir of P. aeruginosa variants lacking expression of the H3-T6SS in patients with chronic but not acute pneumonia. A PAO1 {Delta}H3-T6 mutant caused increased infection in the murine lung as compared to the wild-type strain. The {Delta}H3 mutants exhibited increased transcription of genes involved in phagocytic uptake and respiration under conditions found in the phagolysosome, namely low O2, low pH and abundant itaconate. We confirmed increased intraphagocytic residence of the {Delta}H3 mutants and colocalization with LAMP1 within the phagolysosome of both bone marrow derived macrophages in vitro and in alveolar macrophages harvested directly from infected lungs. Persistence within macrophages required itaconate which preserved the viability of infected macrophages and boosted bacterial bioenergetics to optimize consumption of available carbon sources. Our findings demonstrate that selection for loss of H3-T6SS loss of function mutations promotes the metabolic versatility that enables P. aeruginosa to cause intractable pulmonary infection.

immunology↗

bioRxiv2025

Sequestration of the phagocyte metabolite itaconate by P. aeruginosa RpoN promotes successful pulmonary infection

AbstractThe phagocyte immunometabolite itaconate, normally toxic to bacteria, functions as a signal to stimulate the adaptation of the pulmonary pathogen Pseudomonas aeruginosa to the lung. Itaconate is actively transported into P. aeruginosa where it induces {sigma}54 rpoN expression and co-valently binds cysteine residues on RpoN. RpoN not only functions as a sink to limit itaconate toxicity but S- itaconated RpoN promotes increased utilization of the Entner Doudoroff pathway, optimizing bacterial metabolism in the setting of inflammation. S-itaconation of RpoN directs a global metabolic response that fuels pulmonary infection.

microbiology↗

bioRxiv2025

Regulation of airway fumarate by host and pathogen promotes S. aureus pneumonia

Staphylococcus aureus is a leading cause of healthcare-associated pneumonia, contributing significantly to morbidity and mortality worldwide. As a ubiquitous colonizer of the upper respiratory tract, S. aureus must undergo substantial metabolic adaptation to achieve persistent infection in the distinctive microenvironment of the lung. We observed that fumC, which encodes the enzyme that converts fumarate to malate, is highly conserved with low mutation rates in S. aureus isolates from chronic lung infections. Fumarate, a pro-inflammatory metabolite produced by macrophages during infection, is regulated by the host fumarate hydratase (FH) to limit inflammation. Here, we demonstrate that fumarate, which accumulates in the chronically infected lung, is detrimental to S. aureus, blocking primary metabolic pathways such as glycolysis and oxidative phosphorylation (OXPHOS). This creates a metabolic bottleneck that drives staphylococcal FH (FumC) activity for airway adaptation. FumC not only degrades fumarate but also directs its utilization into critical pathways including the tricarboxylic acid (TCA) cycle, gluconeogenesis and hexosamine synthesis to maintain metabolic fitness and form a protective biofilm. Itaconate, another abundant immunometabolite in the infected airway enhances FumC activity, in synergy with fumarate. In a mouse model of pneumonia, a {Delta}fumC mutant displays significant attenuation compared to its parent and complemented strains, particularly in fumarate- and itaconate-replete conditions. Our findings underscore the pivotal role of immunometabolites in promoting S. aureus pulmonary adaptation.

microbiology↗