# The roles of the Listeria monocytogenes post-translocation chaperones PrsA1 and PrsA2 in protein secretion and stress resistance

## TL;DR

This study explores how two chaperone proteins in Listeria monocytogenes affect protein secretion and stress resistance, revealing their roles in bacterial physiology and conserved functions across related pathogens.

## Contribution

The study identifies novel roles for PrsA1 and PrsA2 in stress resistance and reveals conserved functions of PrsA homologs across gram-positive bacteria.

## Key findings

- Deletion of PrsA1 and PrsA2 in L. monocytogenes disrupts secretion of proteins involved in virulence, cell division, and stress response.
- PrsA homologs in gram-positive bacteria similarly affect pathways related to virulence, cell wall assembly, and stress resistance.
- PrsA1 and PrsA2 contribute to oxidative stress resistance and cell morphology in L. monocytogenes.

## Abstract

PrsA1 and PrsA2 are parvulin peptidyl-prolyl isomerases that function as post-translocation secretion chaperones in Listeria monocytogenes. To assess the contributions of PrsA1 and PrsA2 to overall L. monocytogenes protein secretion, we analyzed prsA1 and prsA2 deletion mutants and PrsA2 structural variants for altered secretion profiles when compared to wild-type bacteria using tandem mass-tagged mass spectrometry. We find that prsA1 and prsA2 deletion mutants have distinctly altered secretion profiles. In addition, among the subset of known secreted proteins with significantly altered secretion abundance were those with characterized functions in virulence, cell division and cell wall assembly, and stress response. To further identify common pathways and protein factors that are altered when PrsA homologs are absent, we conducted a meta-analysis comparing our data from L. monocytogenes to recently published quantitative proteomic secretome data of prsA deletion mutants from diverse gram-positive human pathogens, including Streptococcus pneumoniae, Streptococcus pyogenes, and Staphylococcus aureus. We find that when PrsA homologs are absent in diverse gram-positive bacteria, several pathways are similarly affected, including those promoting bacterial virulence, cell division and cell wall assembly, and oxidative stress resistance. Moreover, we provide evidence of novel roles for L. monocytogenes PrsA1 and PrsA2 in oxidative stress resistance and cell morphology, and PrsA2 in thermo-osmotic stress resistance. Overall, this work suggests that gram-positive PrsA homologs serve in the maturation of multiple protein substrates with varied cellular functions.

Bacterial protein secretion is critical for functions ranging from cell physiology to virulence. Here, we examine the effect of deleting two Listeria monocytogenes secretion chaperones, PrsA1 and PrsA2, and find that in the absence of one or both chaperones, secretion of several proteins implicated in key biological processes was significantly disrupted. These results, coupled with phenotypic observations of chaperone deletion mutants, reveal that PrsA1 and PrsA2 have roles in bacterial physiology and stress resistance. Furthermore, our meta-analysis of prsA deletion mutants in Streptococcus pneumoniae, Streptococcus pyogenes, and Staphylococcus aureus suggests that the contribution of PrsA to critical bacterial processes is well conserved in gram-positive pathogens. Our work lays the foundation for future inquiry investigating the client repertoire of these chaperones.