Quantitative analysis of differential proteome expression in wild-type and mutants strains of Salmonella enterica serovar Typhimurium

The ability to adapt quickly to changing environmental conditions is crucial for growth and survival of bacteria in their natural environment. The common strategy that bacteria utilize to increase their survival under stressful conditions, including antibiotic treatment, is the entry into a non-actively growing state (quiescence). In the wide host-range pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) and other Gram negative bacteria, this temporary arrest of proliferation induces the expression of the alternative sigma subunit σS/RpoS of RNA polymerase (RNAP) which remodels global gene expression to reshape the cell physiology and ensure survival in various stress conditions and nutritional deficiencies (i.e. general stress resistance) and long-term cell persistence. σS is also required for virulence and biofilm formation. Our work aims at understanding key molecular and physiological determinants responsible for persistence of non-growing bacteria, using the ubiquitous pathogen S. Typhimurium as a working system. We expect to identify novel functional proteins that are both physiologically important and of wide biological significance. One approach to characterize those proteins is to compare mutant proteome to that of the wild-type strain to unravel potential effects of the mutations on the expression and/or stability of proteins.