# Roles of Alp and Prt Regulons in the Response of Pseudomonas aeruginosa to UV‐C Light

## TL;DR

This study explores how Pseudomonas aeruginosa responds to UV-C light by activating different genetic pathways, showing that the SOS response is the first to act, followed by Alp and Prt regulons.

## Contribution

The study reveals the distinct timing and roles of Alp and Prt regulons in UV-C response, differing by bacterial subline.

## Key findings

- The LexA-regulated SOS response is the earliest activated pathway after DNA damage.
- The Alp regulon shows delayed induction compared to the SOS response.
- UV-induced cell death is primarily mediated by Alp or Prt systems depending on the subline.

## Abstract

UV light is a well‐studied environmental DNA damaging agent. Bacterial cells respond to UV exposure by upregulating several pathways to repair and tolerate the lesions induced by this agent. The SOS response is the primary pathway activated during genotoxic stress that can shift the balance between mutagenesis and genome integrity. However, in
Pseudomonas aeruginosa
, the canonical SOS response is not the only pathway activated after DNA damage. This opportunistic pathogen also activates the production of pyocins (Prt regulon) and an autolysis pathway controlling the alp genes (Alp regulon) in response to DNA damage. This study aims to characterise gene expression changes in response to UV‐C damage. We performed RNA sequencing analysis to determine the set of differentially expressed genes, and qRT‐PCR to track the course of expression of representative genes from each regulon. Our results show that the canonical LexA‐regulated SOS response is the earliest activated one, while the Alp regulon displays a delayed induction. We also investigated the contribution of the Alp and Prt regulons to UV‐induced cell death and found that the predominant mechanism varies between PAO1 sublines.

Our results show that LexA‐regulated genes are the first to be induced after DNA damage, while autolysis functions controlled by the Alp system are the last. Death by UV is mediated primarily by Alp or Prt systems, depending on the
Pseudomonas aeruginosa
subline.