RESUMO
[This corrects the article DOI: 10.1371/journal.pone.0211584.].
RESUMO
The Cpx-envelope stress system regulates the expression of virulence factors in many Gram-negative pathogens. In Salmonella enterica serovar Typhimurium deletion of the sensor kinase CpxA but not of the response regulator CpxR results in the down regulation of the key regulator for invasion, HilA encoded by the Salmonella pathogenicity island 1 (SPI-1). Here, we provide evidence that cpxA deletion interferes with dephosphorylation of CpxR resulting in increased levels of active CpxR and consequently in misregulation of target genes. 14 potential operons were identified to be under direct control of CpxR. These include the virulence determinants ecotin, the omptin PgtE, and the SPI-2 regulator SsrB. The Tat-system and the PocR regulator that together promote anaerobic respiration of tetrathionate on 1,2-propanediol are also under direct CpxR control. Notably, 1,2-propanediol represses hilA expression. Thus, our work demonstrates for the first time the involvement of the Cpx system in a complex network mediating metabolism and virulence function.
Assuntos
Proteínas de Bactérias/metabolismo , Proteínas Quinases/metabolismo , Salmonella typhi/metabolismo , Salmonella typhi/patogenicidade , Anaerobiose , Regulação Bacteriana da Expressão Gênica , Genômica , Mutação , Fosforilação , Salmonella typhi/genética , VirulênciaRESUMO
The Cpx-envelope stress system coordinates the expression and assembly of surface structures important for the virulence of Gram-negative pathogenic bacteria. It is comprised of the membrane-anchored sensor kinase CpxA, the cytosolic response regulator CpxR and the accessory protein CpxP. Characteristic of the group of two-component systems, the Cpx system responds to a broad range of stimuli including pH, salt, metals, lipids and misfolded proteins that cause perturbation in the envelope. Moreover, the Cpx system has been linked to inter-kingdom signalling and bacterial cell death. However, although signal specificity has been assumed, for most signals the mechanism of signal integration is not understood. Recent structural and functional studies provide the first insights into how CpxP inhibits CpxA and serves as sensor for misfolded pilus subunits, pH and salt. Here, we summarize and reflect on the current knowledge on signal integration by the Cpx-envelope stress system.
Assuntos
Proteínas de Bactérias/fisiologia , Membrana Celular/fisiologia , Bactérias Gram-Negativas/fisiologia , Proteínas de Membrana/fisiologia , Proteínas Quinases/fisiologia , Estresse Fisiológico , Proteínas de Bactérias/química , Membrana Celular/química , Membrana Celular/metabolismo , Fímbrias Bacterianas/genética , Fímbrias Bacterianas/metabolismo , Bactérias Gram-Negativas/patogenicidade , Proteínas de Membrana/química , Dobramento de Proteína , Proteínas Quinases/química , Transdução de SinaisRESUMO
Membrane proteins are crucial for many essential cellular processes. As membrane proteins function in complexes, methods to detect and to characterize membrane protein-protein interactions are undoubtedly required. Therefore, we developed the "Membrane-Strep-tagged protein interaction experiment" (Membrane-SPINE) that combines the specific purification of a Strep-tagged membrane protein with the reversible fixation of protein complexes by formaldehyde cross-linking. In combination with MS analysis, we suggest Membrane-SPINE as a powerful tool to identify unknown interaction partners of membrane proteins in vivo.