The MarR-Type Regulator PA3458 Is Involved in Osmoadaptation Control in Pseudomonas aeruginosa.

Karolina Kotecka,Aneta Agnieszka Bartosik,Adam Kawalek,Kamil Kobylecki

doi:10.3390/ijms22083982

Abstract

Pseudomonas aeruginosa is a facultative human pathogen, causing acute and chronic infections that are especially dangerous for immunocompromised patients. The eradication of P. aeruginosa is difficult due to its intrinsic antibiotic resistance mechanisms, high adaptability, and genetic plasticity. The bacterium possesses multilevel regulatory systems engaging a huge repertoire of transcriptional regulators (TRs). Among these, the MarR family encompasses a number of proteins, mainly acting as repressors, which are involved in response to various environmental signals. In this work, we aimed to decipher the role of PA3458, a putative MarR-type TR from P. aeruginosa. Transcriptional profiling of P. aeruginosa PAO1161 overexpressing PA3458 showed changes in the mRNA level of 133 genes; among them, 100 were down-regulated, suggesting the repressor function of PA3458. Concomitantly, ChIP-seq analysis identified more than 300 PA3458 binding sites in P. aeruginosa. The PA3458 regulon encompasses genes involved in stress response, including the PA3459–PA3461 operon, which is divergent to PA3458. This operon encodes an asparagine synthase, a GNAT-family acetyltransferase, and a glutamyl aminopeptidase engaged in the production of N-acetylglutaminylglutamine amide (NAGGN), which is a potent bacterial osmoprotectant. We showed that PA3458-mediated control of PA3459–PA3461 expression is required for the adaptation of P. aeruginosa growth in high osmolarity. Overall, our data indicate that PA3458 plays a role in osmoadaptation control in P. aeruginosa.

Highlights

Accepted: 9 April 2021P. aeruginosa is a common bacterium that survives in variable environmental conditions, including the human body, and it is the main agent causing nosocomial infections of the lungs, wounds, blood, and urinary tracts [1]
Comparative microarray analysis showed that the PA3459–PA3461 genes were up-regulated in P. aeruginosa cells in response to osmotic stress [9]
Many binding sites of the protein were identified in P. aeruginosa genome predisposing PA3458 to play a role as the global regulator, with one of the direct targets engaged in the production of bacterial osmoprotectant N-acetylglutaminylglutamine amide (NAGGN)

Summary

Introduction

P. aeruginosa is a common bacterium that survives in variable environmental conditions, including the human body, and it is the main agent causing nosocomial infections of the lungs, wounds, blood, and urinary tracts [1]. P. aeruginosa has complex regulatory systems, which allow it to combat environmental stressors with the use of different mechanisms; e.g., in the presence of an antibiotic, cells could use efflux pumps [4] or form biofilm [5]. The multilevel regulatory network allows P. aeruginosa to modulate the metabolism to endure different stress conditions e.g., heat shock [6], the presence of antimicrobials [7], photooxidative [8], or osmotic stress [9,10]. Nineteen prokaryotic transcriptional regulator families have been evaluated so far [12], including the MarR family of transcriptional regulators

Objectives

Methods

Results

Discussion

Conclusion