Global effects of deletions of the sitABCD, mntH, cbiMNQO and corA genes, encoding transporters for manganese, cobalt and magnesium on protein abundance in Salmonella enterica serovar Typhimurium grown to stationary phase in LB.

The RpoS/σS sigma subunit of RNA polymerase is the master regulator of the general stress response in many Gram-negative bacteria.
We have shown that in Salmonella enterica serovar Typhimurium, RpoS activates transcription of the sitABCD and mntH  genes, involved in iron and manganese transport, and that of corA encoding the main magnesium transporter (Levi-Meyrueis et al. 2014, Metaane et al. 2022, Metaane et al. 2023). In addition, RpoS represses expression of the CbiO protein produced from the cbiMNQO operon encoding a high affinity cobalt uptake system (Lago et al. 2017, Metaane et al. 2022, Metaane et al. 2023).  Moreover, Inductively coupled plasma mass spectrometry analyses have revealed that the ΔrpoS mutation reduces the cellular concentration of manganese and magnesium and increases the concentration of cobalt of stationary phase Salmonella (Metaane et al. 2022). These findings suggested that a tight control of uptake and availability of manganese, magnesium and cobalt might be critical for quiescent bacteria. Consistent with this hypothesis, our recent findings unraveled the importance of RpoS and magnesium in the regrowth potential of quiescent Salmonella cells (Metaane et al. 2022).
Unexpectedly, our recent work revealed that, under magnesium proficient environmental conditions, the absence of the housekeeping Mg2+ transporter CorA is sensed by the cell which induces compensatory mechanisms to minimize the impact of a ΔcorA mutation on protein content, magnesium homeostasis, growth, and motility of Salmonella (Metaane et al. 2023). In this study, we used a mass spectrometry-based proteomics approach to address the physiological impact of the SitABCD, MntH and CbiMNQO transporters on quiescent  Salmonella. A comprehensive quantitative proteomic analysis was performed using wild-type and ΔrpoS strains of Salmonella ATCC14028 carrying deletions of these genes and grown to late stationary phase in nutrient-rich LB medium, i.e. the growth conditions previously used to characterize the RpoS- transcriptome, proteome and ionome (Levi-Meyrueis et al. 2014, Lago et al. 2017, Metaane et al. 2022). Since CorA can also import cobalt, a ΔcorA mutation was included and combined with the ΔcbiMNQO mutation.     
Accession number.The mass spectrometry proteomics data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with the dataset identifier PXD043760.
This work was supported by the French National Research Agency (ANR-19-CE44-0005-01, PERIOMET project).
References
Levi-Meyrueis C, Monteil V, Sismeiro O, Dillies MA, Monot M, Jagla B, Coppée J-Y, Dupuy B, Norel F. Expanding the RpoS/sigmaS-network by RNA sequencing and identification of sigmaS-controlled small RNAs in Salmonella. PloS one. 2014;9(5):e96918.
Lago M, Monteil V, Douche T, Guglielmini J, Criscuolo A, Maufrais C, Matondo M, Norel F. Proteome remodelling by the stress sigma factor RpoS/sigma(S) in Salmonella: identification of small proteins and evidence for post-transcriptional regulation. Scientific reports. 2017;7(1):2127.
Metaane S, Monteil V, Ayrault S, Bordier L, Levi-Meyreuis C, Norel F. The stress sigma factor sigmaS/RpoS counteracts Fur repression of genes involved in iron and manganese metabolism and modulates the ionome of Salmonella enterica serovar Typhimurium. PLoS one. 2022;17(3):e0265511.
Metaane S, Monteil V, Douché T, Giai Gianetto Q, Matondo M, Maufrais C, Norel F. Loss of CorA, the primary magnesium transporter of Salmonella, is alleviated by MgtA and PhoP-dependent compensatory mechanisms. PloS one 2023;18(9):e0291736.
NOREL, & MONTEIL. (2023). Ionome analysis of Salmonella mutants by Inductively coupled plasma mass spectrometry (ICP-MS) (Version v1) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.8085835