Abstract

Salmonella is a primary cause of enteric diseases in a variety of animals. During its evolution into a pathogenic bacterium, Salmonella acquired an elaborate regulatory network that responds to multiple environmental stimuli within host animals and integrates them resulting in fine regulation of the virulence program. The coordinated action by this regulatory network involves numerous virulence regulators, necessitating genome-wide profiling analysis to assess and combine efforts from multiple regulons. In this review we discuss recent high-throughput analytic approaches used to understand the regulatory network of Salmonella that controls virulence processes. Application of high-throughput analyses have generated large amounts of data and necessitated the development of computational approaches for data integration. Therefore, we also cover computer-aided network analyses to infer regulatory networks, and demonstrate how genome-scale data can be used to construct regulatory and metabolic systems models of Salmonella pathogenesis. Genes that are coordinately controlled by multiple virulence regulators under infectious conditions are more likely to be important for pathogenesis. Thus, reconstructing the global regulatory network during infection or, at the very least, under conditions that mimic the host cellular environment not only provides a bird's eye view of Salmonella survival strategy in response to hostile host environments but also serves as an efficient means to identify novel virulence factors that are essential for Salmonella to accomplish systemic infection in the host.

Highlights

  • Salmonellae are Gram-negative facultative pathogens that live in diverse environments and infect a wide variety of animals

  • DNA bending protein required for site specific recombination of the flagellar phase variation protein hin; regulates Salmonella pathogenicity island (SPI)-1 Transcriptional regulator containing a highly conserved domain of unknown function Two-component regulator that responds to low Mg and defensins SPI-2 encoded two-component regulator required for systemic infection Tunes regulation of SPI-2 more precisely than SsrA/SsrB alone; controls regulation of many virulence factors Responds to cAMP levels which are determined in part by external glucose concentration Two-component regulator that responds to osmolarity Controls carbon metabolism Required for bacteriophage lambda integration; bends DNA and significantly changes transcriptional regulation of many genes Required for the bacterial stringent response that results in reduced transcription in the presence of uncharged t-RNA MarR family transcription regulator

  • Genes that are coordinately controlled by multiple virulence regulators under infectious conditions and show a similar expression profile to that of well-known virulence genes are more likely to be important for pathogenesis

Read more

Summary

Background

Salmonellae are Gram-negative facultative pathogens that live in diverse environments and infect a wide variety of animals. SPI-2 is induced during intracellular Salmonella infection of a variety of cell types (Geddes et al, 2007) and secretes dozens of distinct effector proteins (Niemann et al, 2011) Mutation of this T3SS does not have a huge effect on intramacrophage survival, it does result in completely abrogating infection in mice (Buchmeier and Heffron, 1991; Poh et al, 2008). While most known Salmonella effectors have been found to be secreted by the SPI-2 or SPI-1 T3SS (Steele-Mortimer, 2008; McGhie et al, 2009; Niemann et al, 2011), some have been shown to utilize both the SPI-1 and SPI-2 T3SSs for efficient secretion (Haraga et al, 2008) This complex mixture of secretion processes for Salmonella effectors suggests that there are multiple levels of regulation from transcription to translation to the secretion apparatus each level is critical for the virulence program of these pathogens. We focus here on the application of high-throughput and/or global methodologies to measure virulence and regulatory aspects of Salmonella, the computational approaches used to determine regulatory networks, and how this information can be used to construct systems models/simulations of Salmonella pathogenesis (Figure 1)

Experimental methods to determine regulatory networks
Computational Methods
Findings
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call