Proteome of Salmonella Enterica Serotype Typhimurium Grown in a Low Mg2+/pH Medium

Abstract

To determine the impact of a low Mg2+/pH defined growth medium (MgM) on the proteome of Salmonella enterica serotype Typhimurium, we cultured S. Typhimurium cells in the medium under two different conditions termed MgM Shock and MgM Dilution and then comparatively analyzed the bacterial cells harvested from these conditions by a global proteomic approach. Proteomic results showed that MgM Shock and MgM Dilution differentially affected the S. Typhimurium proteome. MgM Shock induced a group of proteins whose induction usually occurred at low O2 level, while MgM Dilution induced those related to the type III secretion system (T3SS) of Salmonella Pathogenicity Island 2 (SPI2) and those involved in thiamine or biotin biosynthesis. The metabolic state of the S. Typhimurium cells grown under MgM Shock condition also differed significantly from that under MgM Dilution condition. Western blot analysis not only confirmed the proteomic results, but also showed that the abundances of SPI2-T3SS proteins SsaQ and SseE and biotin biosynthesis proteins BioB and BioD increased after S. Typhimurium infection of RAW 264.7 macrophages. Deletion of the gene encoding BioB reduced the bacterial ability to replicate inside the macrophages, suggesting a biotin-limited environment encountered by S. Typhimurium within RAW 264.7 macrophages.

Biotin sulfoxide reductase contributes to oxidative stress tolerance and virulence in Salmonella enterica serovar Typhimurium

“…Recent studies highlighted the impact of de novo biotin biosynthesis especially for intracellular pathogens like M. tuberculosis, F. tularensis and S. Typhimurium (Dey et al, 2010;Napier et al, 2012;Shi et al, 2009;Woong Park et al, 2011). Here the in vivo attenuation of both the biotin auxotrophic DbioB mutant and the DbisC mutant emphasized the importance of biotin homeostasis during infection and demonstrated that BisC was crucial for full virulence of S. Typhimurium.…”

“…As a result, BisC allowed S. Typhimurium to regenerate biotin and methionine from their oxidized forms. This could be advantageous, especially for an intracellular lifestyle when energy sources and nutrients are scarce (Buchmeier & Libby, 1997;Chakravortty et al, 2002;Fields et al, 1986;Gallois et al, 2001;García-del Portillo et al, 2008;Hoiseth & Stocker, 1981;Shi et al, 2009). …”

“…It has been reported that S. Typhimurium relies on biotin biosynthesis for intracellular replication (Shi et al, 2009). Hence, we generated a biotin auxotrophic mutant (DbioB), and showed that replication was impaired both in nonstimulated and in IFN-c activated macrophages (Fig.…”

“…The de novo biotin biosynthesis pathway has been shown to be essential for pathogenesis of intracellular bacteria such as Mycobacterium tuberculosis, Francisella tularensis and S. Typhimurium (Dey et al, 2010;Napier et al, 2012;Shi et al, 2009;Woong Park et al, 2011). In this study, we characterized the role of BisC in the oxidative stress response and virulence of S. Typhimurium.…”

Proteomic Analyses of Intracellular Salmonella enterica Serovar Typhimurium Reveal Extensive Bacterial Adaptations to Infected Host Epithelial Cells

“…Such measurements, however, have been technically challenging due to the presence of vast amounts of host proteins (7). As a matter of fact, until now Ͼ90% of Salmonella proteomics research has focused on bacteria grown in vitro either from different strains or under culture conditions with various perturbations (8,9,10,11,12,13,14,15,16,17).…”