Ionome analysis of of Salmonella mutants by Inductively coupled plasma mass spectrometry (ICP-MS)

In many Gram-negative bacteria, the stress sigma factor of RNA polymerase, σ^S/RpoS, remodels global gene expression to reshape the physiology of quiescent cells and ensure their survival under non-optimal growth conditions. In the foodborne pathogen <em>Salmonella enterica</em> serovar Typhimurium, σ^S is also required for biofilm formation and virulence. We have previously shown that a Δ<em>rpoS</em> mutation affects the <em>Salmonella</em> ionome. Indeed, inductively coupled plasma mass spectrometry analyses have unraveled a significant effect of the Δ<em>rpoS </em>mutation on the cellular concentration of manganese, magnesium, cobalt and potassium, suggesting that σ^S controls fluxes of ions that might be important for the fitness of quiescent cells (Metaane et al. 2022, PLoS ONE 17(3): e0265511). Study: These findings prompted us to evaluate the impact on the<em> Salmonella</em> ionome of deletions of genes encoding the <em>Salmonella</em> Mn²⁺ transporters (<em>sitABCD</em> and <em>mntH</em>), the Co²⁺ transporter (<em>cbiMNQO</em> operon) and small proteins of unkown function (<em>yqaE</em> and <em>yqjDEK</em>) that accumulate in quiescent <em>Salmonella</em> under the tight control of σ^S (Levi-Meyrueis et al. PloS one. 2014; 9(5):e96918, Lago et al. Scientific reports. 2017; 7(1):2127 and Metaane et al. 2022, PLoS ONE 17(3): e0265511). Material and Methods: Cell-associated contents of several elements were measured by inductively coupled plasma mass spectrometry (ICP-MS) as previously described in Metaane <em>et al </em>2022 PLoS ONE 17(3): e0265511.Dried cell pellets were prepared by V. Monteil and F. Norel (Institut Pasteur, Université de Paris, CNRS UMR3528, Biochimie des Interactions Macromoléculaires, F-75015, Paris, France). Cell-associated contents of several elements were measured by S. Ayrault and L. Bordier (ICP-MS platform, Laboratoire des Sciences du Climat et de l’Environnement, LSCE/IPSL, CEA-CNRSUVSQ,Université Paris-Saclay, 91191, Gif-sur-Yvette, France)