Hibernation factors and ribosomal dynamics of dormancy in Pseudomonas aeruginosa

Abstract

Microbial dormancy is a strategy employed by most microorganisms to endure challenging environmental conditions. The work described here explores the dormancy and hibernation of Pseudomonas aeruginosa, a major human pathogen. P. aeruginosa is responsible for infecting burn wound victims, patients with cystic fibrosis, individuals with compromised immune systems, and those with chronic respiratory conditions. It can cause a wide range of infections, including pneumonia, urinary tract infections, and bloodstream infections. Dormancy allows P. aeruginosa to survive antibiotic treatments and evade host immune responses, enabling it to persist in the body for extended periods and complicate treatment efforts. Dormancy and hibernation are closely linked to ribosomal activity. A hibernating cell and an active cell can be distinguished by the activity of their ribosomes, as ribosomal function nearly ceases during dormancy. The aim of the work described here is to uncover the molecular mechanisms behind dormancy of P. aeruginosa. We approach this by studying the proteins that bind to the ribosome and induce dormancy, known as dormancy factors. We established a fluorescence-based reporter system known as bimolecular fluorescence complementation (BiFC) to track the dormancy factors and their binding to the ribosome. Using this method, we studied all of the major dormancy factors of P. aeruginosa and gained insights into their function. In addition, we describe a controversial ribosomal accessory protein, ribosomal silencing factor (RsfS), which we found to be present on the ribosomes of P. aeruginosa. We characterized this protein's function and its influence on the ribosomes. Finally, we describe the components of the stringent response signaling pathway and provide further insights into how it influences dormancy and dormancy factors. Not only does this work strengthen the link between dormancy and the stringent response, but it also offers insights into potential interactions with other signaling pathways.