The absence of SigX results in impaired carbon metabolism and membrane fluidity in Pseudomonas aeruginosa

Maud Fléchard, Rachel Duchesne, Ali Tahrioui, Emeline Bouffartigues, Ségolène Depayras, Julie Hardouin, Coralie Lagy, Olivier Maillot, Damien Tortuel, Cecil Onyedikachi Azuama, Thomas Clamens, Cécile Duclairoir-Poc, Manuella Catel-Ferreira, Gwendoline Gicquel, Marc G J Feuilloley, Olivier Lesouhaitier, Hermann J Heipieper, Marie-Christine Groleau, Éric Déziel, Pierre CornelisSylvie Chevalier

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

In Pseudomonas aeruginosa, SigX is an extra-cytoplasmic function σ factor that belongs to the cell wall stress response network. In previous studies, we made the puzzling observation that sigX mutant growth was severely affected in rich lysogeny broth (LB) but not in minimal medium. Here, through comparative transcriptomic and proteomic analysis, we show that the absence of SigX results in dysregulation of genes, whose products are mainly involved in transport, carbon and energy metabolisms. Production of most of these genes is controlled by carbon catabolite repression (CCR), a key regulatory system than ensures preferential carbon source uptake and utilization, substrate prioritization and metabolism. The strong CCR response elicited in LB was lowered in a sigX mutant, suggesting altered nutrient uptake. Since the absence of SigX affects membrane composition and fluidity, we suspected membrane changes to cause such phenotype. The detergent polysorbate 80 (PS80) can moderately destabilize the envelope resulting in non-specific increased nutrient intake. Remarkably, growth, membrane fluidity and expression of dysregulated genes in the sigX mutant strain were restored in LB supplemented with PS80. Altogether, these data suggest that SigX is indirectly involved in CCR regulation, possibly via its effects on membrane integrity and fluidity.

Original languageEnglish
Article number17212
Number of pages13
JournalScientific Reports - Nature
Volume8
Issue number1
DOIs
Publication statusPublished - 21 Nov 2018

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