Luecke, A. | bioRxiv Science

bioRxiv2026

Proton motive force mediated efflux mismatch drives gentamycin-novobiocin collateral sensitivity in Pseudomonas aeruginosa

Resistance to a particular antibiotic can make bacteria sensitive to others, a phenomenon known as collateral sensitivity (CS). This study explored potential CS in clinical and experimentally evolved drug-resistant Pseudomonas aeruginosa (PA) and investigated underlying mechanisms. Whole-genome sequencing and RNA-seq were analyzed to identify genetic and transcriptional correlations. In vitro efficacies were assessed with co-and sequential-exposure regimens. Multiple CF isolates and experimentally evolved gentamycin (GEN) resistant strains consistently exhibited strong CS to novobiocin (NOV). Comparative genomics revealed pmrB gain-of-function mutations, which was further supported by transcriptomic signatures of pmrAB activation. Transcriptomic data suggests potential outer-membrane remodeling characterized by polyamine accumulation and compromised porin channel expression. Additionally, the reduction in proton motive force (PMF) further explains the possible mechanism underlying GEN resistance. As NOV efflux is PMF-dependent, this energetic deficit created a PMF-efflux mismatch, leading to hypersensitivity to NOV. Notably, sequential GEN[->]NOV treatment effectively restricted the emergence of GEN resistant subpopulations. Overall, our data suggest GEN resistance in PA may arises through envelope remodeling and reduced PMF, which impairs efflux pumps and creates hypersensitivity to NOV. Exploiting this PMF-efflux mismatch with sequential treatment effectively restricted the emergence of GEN resistance.

microbiology↗

bioRxiv2025

Systems-level Plant Responses Reveal Pseudomonas-Mediated Growth Promotion in Brachypodium Under Nitrogen Limitation

Plant molecular adaptation to plant growth promoting bacteria (PGPB) under nutrient stress remains unclear, yet is essential for advancing PGPB use in agriculture. The model grass Brachypodium dystachion was studied together with Pseudomonas koreeensis (Pk) at two nitrogen (N) conditions. Non-invasive shoot phenotyping showed an immediate response to low-N, while beneficial effects of Pk became quantifiable after day 19. Increased N content in inoculated plants, along with Pks ability to grow on N-free media, suggests bacterial N contribution at deficient N. In low-N conditions, Pk-inoculated plants showed 33.2% more N than uninoculated controls and biomass comparable to high-N plants. Pk had no effect under sufficient N. Proteomics and lipidomics revealed that lipid profiles were primarily shaped by N availability, while protein abundance responded to both Pk and N status. Inoculated low-N plants displayed protein profiles resembling those of high-N controls, with some distinct exceptions. The plant-microbe interaction is dynamic and developed over 3 weeks, leading to increased biomass and N content. Root proteins strongly induced by Pk under low-N included lipid degradation enzymes, N transporters, and regulatory proteins, suggesting a coordinated remodelling of energy metabolism supporting whole-plant biomass and increased abundance of N uptake proteins.

plant biology↗