The H‐NS‐like protein StpA represses the RpoS (σ³⁸) regulon during exponential growth of Salmonella Typhimurium

Abstract

SummaryStpA is a paralogue of the nucleoid-associated protein H-NS that is conserved in a range of enteric bacteria and had no known function in Salmonella Typhimurium. We show that 5% of the Salmonella genome is regulated by StpA, which contrasts with the situation in Escherichia coli where deletion of stpA only had minor effects on gene expression. The StpA-dependent genes of S. Typhimurium are a specific subset of the H-NS regulon that are predominantly under the positive control of s 38 (RpoS), CRP-cAMP and PhoP. Regulation by StpA varied with growth phase; StpA controlled s 38 levels at mid-exponential phase by preventing inappropriate activation of s 38 during rapid bacterial growth. In contrast, StpA only activated the CRP-cAMP regulon during late exponential phase. ChIP-chip analysis revealed that StpA binds to PhoP-dependent genes but not to most genes of the CRP-cAMP and s 38 regulons. In fact, StpA indirectly regulates s 38 -dependent genes by enhancing s 38 turnover by repressing the anti-adaptor protein rssC. We discovered that StpA is essential for the dynamic regulation of s 38 in response to increased glucose levels. Our findings identify StpA as a novel growth phasespecific regulator that plays an important physiological role by linking s 38 levels to nutrient availability.

Roles of Nucleoid-Associated Proteins in Stress-Induced Mutagenic Break Repair in StarvingEscherichia coli

“…Of 15 NAPs, 7 studied here and 5 studied previously (reviewed later), only 2, StpA, an analog of H-NS (Lucchini et al 2009), and Hha did not affect MBR (Figure 1). Surprisingly, the various NAPs appear to modulate MBR by different mechanisms (summarized in Table 2) nearly all positively, and many, but not all, centered on stress-response regulation.…”

The General Stress Response σS Is Regulated by a Partner Switch in the Gram-negative Bacterium Shewanella oneidensis

“…These proteins interact with RssB and prevent the degradation of S , leading thus to S accumulation in the cell. Surprisingly, except for enterobacteria, the post-translational regulation of S is unknown in other Gram-negative bacteria (21)(22)(23).…”

Weighted Meta-Analysis for Small Sample Microarray Studies

“…This study had two experiments. Findings from both studies are published in [23]. They demonstrated that the stpA protein is not produced in substantial quantities in the wildtype during the early log or stationary stages [23].…”

“…Findings from both studies are published in [23]. They demonstrated that the stpA protein is not produced in substantial quantities in the wildtype during the early log or stationary stages [23]. They also concluded that the RpoS knockout counteracted some of the gene expression effects of stpA deletion [23].…”

“…We identified two composite studies conducted by Lucchini et al [23], that met all of these criteria. One of these studies, GSE18424, compared transcription rates of wildtype S. enterica Typhimurium and a derivative stpA knockout strain, at the early log, mid log, late log, and stationary growth stages in the lifecycle of a culture.…”