Mechanical Genomic Studies Reveal the Role of d -Alanine Metabolism in Pseudomonas aeruginosa Cell Stiffness

Abstract

The mechanical properties of bacteria are important for protecting cells against physical stress. The cell wall is the best-characterized cellular element contributing to bacterial cell mechanics; however, the biochemistry underlying its regulation and assembly is still not completely understood. Using a unique high-throughput biophysical assay, we identified genes coding proteins that modulate cell stiffness in the opportunistic human pathogen Pseudomonas aeruginosa . This approach enabled us to discover proteins with roles in a diverse range of biochemical pathways that influence the stiffness of P. aeruginosa cells. We demonstrate that d -Ala—a component of the peptidoglycan—is tightly regulated in cells and that its accumulation reduces expression of machinery that cross-links this material and decreases cell stiffness. This research demonstrates that there is much to learn about mechanical regulation in bacteria, and these studies revealed new nonessential P. aeruginosa targets that may enhance antibacterial chemotherapies or lead to new approaches.