Role of phoU in P. aeruginosa virulence and the emergence of compensatory mutations in the ΔphoU mutant
- 1Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP Brazil
- 2Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
Abstract
Bacteria respond to phosphate (Pi) availability by modulating the PHO regulon, which encodes proteins for Pi scavenging. The phoU gene is part of the pst operon, a high-affinity phosphate transport system that also represses PHO regulon expression under Pi excess. In the absence of phoU, Pi transport continues but repression fails, resulting in constitutive PHO gene transcription. In Pseudomonas aeruginosa and other Proteobacteria, phoU knockouts display pleiotropic effects, including stress and antibiotic sensitivity and polyphosphate (polyP) accumulation. Here, using cryo-STEM imaging and EDX analysis, we show that the ΔphoU mutant of P. aeruginosa accumulates large polyP granules containing over seven-fold more phosphorus than the wild type. Moreover, ΔphoU was markedly less virulent in vivo in the Galleria mellonella model. We further isolated two suppressor classes from ΔphoU: low-constitutive alkaline phosphatase (LCAP) and not-constitutive alkaline phosphatase (NCAP). LCAP mutants remain PHO-constitutive, less virulent than wild type, and accumulate polyP similarly to ΔphoU. In contrast, NCAP mutants are not PHO-constitutive, do not accumulate polyP, and retain wild-type virulence. We also tested swarming motility, pyocyanin, and pyoverdine production. Significant differences were limited to swarming, where ΔphoU was substantially less motile than the wild type, with LCAP showing partial recovery and NCAP full restoration.
Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1186/s12866-026-05442-5.
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BibTeX
@article{machado2026role,
title = {{Role of phoU in P. aeruginosa virulence and the emergence of compensatory mutations in the ΔphoU mutant}},
author = {Gabriella T. Machado and Nicole Gonçalves Picinin and Danilo Ferraz and Luiz Gustavo de Almeida and Luciana Thomaz and Sharon G. Wolf and Michael Elbaum and Beny Spira},
journal = {BMC Microbiology},
year = {2026},
month = jul,
doi = {10.1186/s12866-026-05442-5},
url = {https://doi.org/10.1186/s12866-026-05442-5},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Role of phoU in P. aeruginosa virulence and the emergence of compensatory mutations in the ΔphoU mutant
AU - Gabriella T. Machado
AU - Nicole Gonçalves Picinin
AU - Danilo Ferraz
AU - Luiz Gustavo de Almeida
AU - Luciana Thomaz
AU - Sharon G. Wolf
AU - Michael Elbaum
AU - Beny Spira
PY - 2026
DA - 2026/07/30
JO - BMC Microbiology
DO - 10.1186/s12866-026-05442-5
UR - https://doi.org/10.1186/s12866-026-05442-5
AB - Bacteria respond to phosphate (Pi) availability by modulating the PHO regulon, which encodes proteins for Pi scavenging. The phoU gene is part of the pst operon, a high-affinity phosphate transport system that also represses PHO regulon expression under Pi excess. In the absence of phoU, Pi transport continues but repression fails, resulting in constitutive PHO gene transcription. In Pseudomonas aeruginosa and other Proteobacteria, phoU knockouts display pleiotropic effects, including stress and antibiotic sensitivity and polyphosphate (polyP) accumulation. Here, using cryo-STEM imaging and EDX analysis, we show that the ΔphoU mutant of P. aeruginosa accumulates large polyP granules containing over seven-fold more phosphorus than the wild type. Moreover, ΔphoU was markedly less virulent in vivo in the Galleria mellonella model. We further isolated two suppressor classes from ΔphoU: low-constitutive alkaline phosphatase (LCAP) and not-constitutive alkaline phosphatase (NCAP). LCAP mutants remain PHO-constitutive, less virulent than wild type, and accumulate polyP similarly to ΔphoU. In contrast, NCAP mutants are not PHO-constitutive, do not accumulate polyP, and retain wild-type virulence. We also tested swarming motility, pyocyanin, and pyoverdine production. Significant differences were limited to swarming, where ΔphoU was substantially less motile than the wild type, with LCAP showing partial recovery and NCAP full restoration. Supplementary Information: The online version contains supplementary material available at https://doi.org/10.1186/s12866-026-05442-5.
SN - 1471-2180
ER -