# Group A streptococcal PerR coordinates iron and zinc homeostasis through Dpr, aiding in bacterial fitness during endothelial cell infection

## TL;DR

This study shows how a bacterial regulator called PerR helps group A Streptococcus survive in human cells by managing iron and zinc levels.

## Contribution

The study reveals that PerR coordinates iron and zinc homeostasis through Dpr, enhancing bacterial fitness during infection.

## Key findings

- PerR regulates zinc and iron homeostasis in GAS, using Dpr and other proteins.
- Zinc restriction in phagolysosomes reduces survival of the ΔperR mutant.
- PerR-mediated metal modulation is crucial for GAS fitness during endothelial cell invasion.

## Abstract

Streptococcus pyogenes (group A Streptococcus, GAS) causes various clinical complications and invasive diseases. Our previous studies have shown that GAS survives inside endothelial cells due to the insufficient acidification of lysosomes, which fuse with reactive oxygen species (ROS)-induced phagosomes of LC3-associated phagocytosis. For catalase-deficient peroxide-producing GAS to survive in hosts, GAS uses a peroxide response regulator (PerR) to modulate ROS-induced oxidative stress and metal ion regulation. However, it remains unclear whether PerR regulates zinc homeostasis during infections. We generated the GAS ΔperR isogenic mutant and conducted dual RNA-seq analysis, an endothelial cell infection model, computational predictions, and phenotypic characterization to demonstrate the protective role of PerR in GAS survival in endothelial cells. The ΔperR mutant’s vulnerability to zinc deprivation demonstrated that PerR coordinates iron and zinc homeostasis, likely using PmtA’s iron efflux, iron and zinc-chelating ferritin-like Dpr, the AdcR regulon (adcA, adcAII, and phtD), and zinc efflux (czcD). We also demonstrated that the wild-type strain and ΔperR mutant encounter zinc restriction inside the phagolysosome GAS-containing vacuoles of endothelial cells. This host zinc starvation severely reduces the survival of the ΔperR mutant. These results suggest that the PerR-mediated iron and zinc modulation through Dpr is more important than had been previously thought. Consequently, PerR enhances GAS fitness during its invasions of human endothelial cells.

Our study combines dual RNA-seq analysis, an endothelial cell infection model, computational predictions, and phenotypic characterization to discover the impact of group A Streptococcus (GAS) PerR on the coordination of iron and zinc homeostasis during infection. We found that PmtA’s iron efflux, iron and zinc-chelating ferritin-like Dpr, the AdcR regulon, and zinc efflux are delicately modulated by PerR. We also determined that zinc limitation inside the phagolysosome GAS-containing vacuoles of endothelial cells causes host zinc starvation, resulting in reduced survival of the ΔperR mutant. Consequently, PerR enhances GAS fitness through Dpr during its invasions of human endothelial cells. Our novel findings offer new insights into how GAS combats iron-mediated oxidative stress and zinc homeostasis that may help develop new anti-GAS treatments.