Genetic and phenotypic characterization of the RyhB regulon in Salmonella Typhimurium

Kim, Jeong Nam; Kwon, Young Min

doi:10.1016/j.micres.2012.06.007

Cited by 44 publications

(43 citation statements)

References 33 publications

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“…Deletion of either rfrA or rfrB or both small RNA genes resulted in a growth curve similar to the wild-type strain, in either low or high iron conditions. These results are consistent with a previous report in S. Typhimurium (Kim & Kwon, 2013). Overall, the growth profile of the mutants was similar between the high and low iron conditions except that the final growth level was lower in low iron conditions.…”

Section: Growth Of the Mutant Strains In High And Low Iron Conditionssupporting

confidence: 93%

“…We could interpret the intermediate level of sensitivity of the double mutants (fur/rfrA and fur/rfrB) as the two sRNAs working additively, an observation that is reinforced by a regain in resistance of the fur mutant after loss of both of these sRNAs. In S. Typhimurium, similar results were shown, but only the fur/ryhB-1 (fur/ rfrA) mutant showed significantly higher resistance compared with the fur mutant, but not the fur/ryhB-2 (fur/rfrB) or the triple mutant (Kim & Kwon, 2013). This suggests that some differences in the role of the sRNAs may exist between these two serovars.…”

Section: Sensitivity Of the Mutant Strains To Oxidative Stresssupporting

confidence: 66%

“…Unlike E. coli, Salmonella possesses two sRNAs, RfrA (also called RyhB, RyhB-1) and RfrB (also called IsrE, , that are the orthologue and paralogue of RyhB, respectively (Ellermeier & Slauch, 2008;Kim & Kwon, 2013;Ortega et al, 2012;Padalon-Brauch et al, 2008). S. enterica serovar Typhi (S. Typhi) rfrA and rfrB genes respectively share 81.1 and 70 % identity with the E. coli ryhB gene, and rfrA shares 65.6 % identity with rfrB.…”

Section: Introductionmentioning

confidence: 99%

“…RfrA and RfrB of S. Typhimurium are overexpressed in cultured murine macrophages (PadalonBrauch et al, 2008), but their role in virulence has not been reported. Recently, some targets regulated by these two sRNAs (RyhB-1 and RyhB-2) were identified in S. Typhimurium (Kim & Kwon, 2013). It was shown that both sRNAs are implicated in some cellular pathways, where differences in their functions showed that they do not act redundantly in most cases (Kim & Kwon, 2013).…”

Section: Introductionmentioning

confidence: 99%

“…Recently, some targets regulated by these two sRNAs (RyhB-1 and RyhB-2) were identified in S. Typhimurium (Kim & Kwon, 2013). It was shown that both sRNAs are implicated in some cellular pathways, where differences in their functions showed that they do not act redundantly in most cases (Kim & Kwon, 2013). Also, RfrA and RfrB expression was shown to be induced inside fibroblast cells, and loss of these sRNAs increased intracellular bacterial growth (Ortega et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

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Role of the Salmonella enterica serovar Typhi Fur regulator and small RNAs RfrA and RfrB in iron homeostasis and interaction with host cells

Leclerc

Dozois

2013

Microbiology

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Iron is an essential element but can be toxic at high concentrations. Therefore, its acquisition and storage require tight control. Salmonella encodes the global regulator Fur (ferric uptake regulator) and the small regulatory non-coding RNAs (sRNAs) RfrA and RfrB, homologues of RyhB. The role of these iron homeostasis regulators was investigated in Salmonella enterica serovar Typhi (S. Typhi). Strains containing either single or combined deletions of these regulators were obtained. The mutants were tested for growth in low and high iron conditions, resistance to oxidative stress, expression and production of siderophores, and during interaction with host cells. The fur mutant showed a growth defect and was sensitive to hydrogen peroxide. The expression of the sRNAs was responsible for these defects. Siderophore expression by S. Typhi and both sRNAs were regulated by iron and by Fur. Fur contributed to invasion of epithelial cells, and was shown for the first time to play a role in phagocytosis and intracellular survival of S. Typhi in human macrophages. The sRNAs RfrA and RfrB were not required for interaction with epithelial cells, but both sRNAs were important for optimal intracellular replication in macrophages. In S. Typhi, Fur is a repressor of both sRNAs, and loss of either RfrA or RfrB resulted in distinct phenotypes, suggesting a non-redundant role for these regulatory RNAs.

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Section: Growth Of the Mutant Strains In High And Low Iron Conditionssupporting

confidence: 93%

Section: Sensitivity Of the Mutant Strains To Oxidative Stresssupporting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Role of the Salmonella enterica serovar Typhi Fur regulator and small RNAs RfrA and RfrB in iron homeostasis and interaction with host cells

Leclerc

Dozois

2013

Microbiology

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Phenotypic Characterization of Salmonella RyhB-1 Mutations that Modulate Target Regulation

Kim

Kwon

2014

Curr Microbiol

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Recently, we reported the global regulatory roles of the two small RNAs in Salmonella typhimurium, ryhB-1 and ryhB-2. However, the genetic basis of the sRNA-target interactions remains unknown. To identify the nucleotides of RyhB-1 that are functionally important for its regulatory actions, we introduced random single-point mutations into ryhB-1 gene on the chromosome of Salmonella typhimurium carrying a sodB-lacZ translational fusion by an error-prone PCR method. We reasoned that mutants expressing variant RyhB-1 with weakened interaction with sodB transcript would produce a higher level of SodB when compared to wild type, leading to darker blue colonies on X-gal agar plates. Five mutants displaying a significant increase in β-galactosidase activity under the condition inducing RyhB-1 expression were isolated. Quantitative real-time PCR analysis showed that the expression levels of eight target mRNAs in these five mutants were significantly changed when compared to the parent strain. Interestingly, two mutations affected growth and cell survival under H2O2-stressed conditions. The results suggest that there are strong selective constraints against mutational changes in ryhB-1 gene sequence, leading to high levels of nucleotide conservation in ryhB-1 gene sequences among the genus of Salmonella.

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Genetics of CRISPR arrays in Salmonella Typhimurium 14028 associated with foreign DNA decay

Kim

2018

Genes Genom

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Clustered regularly interspaced short palindromic repeats (CRISPRs) are a genetic locus of prokaryotes and contain highly conserved direct repeats, spacers, and CRISPR-associated genes. Spacers in CRISPRs are known as adaptive immune markers and reveal what types of phage or foreign DNA have been introduced in the past. The primary objective of this study was to analyze spacer sequences in CRISPR arrays of 15 Salmonella enterica subspecies and to determine if Salmonella CRISPRs are indeed involved in resistance to foreign DNAs. Using a bioinformatics algorithm, the CRISPR arrays of 15 subspecies of S. enterica were predicted. The transformation efficiencies of the wild-type and mutant strains lacking a space were determined using the plasmid harboring the same sequences with the space. Analysis of the CRISPR arrays indicated that S. Typhimurium encoded three possible CRISPR regions in the genome. Notably, 48 or 55 spacers were predicted in the genomes of S. Typhimurium 14028 and LT2 strains, respectively, and 39 were precisely identical. To confirm this prediction, the predicted CRISPR regions of S. Typhimurium 14028 were sequenced using the specific primers. Interestingly, a homology search of individual spacers found that the 2nd spacer of CRISPR 2 was nearly identical to a partial genome region of phage FSL SP-016. The mutant strain showed two to threefold increased transformation efficiency compared to that of the wild-type strain. These results demonstrate that the spacer sequence is dependent on genetic relations, especially for adaptive immunity against phage or foreign DNAs.

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Genetic and phenotypic characterization of the RyhB regulon in Salmonella Typhimurium

Cited by 44 publications

References 33 publications

Role of the Salmonella enterica serovar Typhi Fur regulator and small RNAs RfrA and RfrB in iron homeostasis and interaction with host cells

Role of the Salmonella enterica serovar Typhi Fur regulator and small RNAs RfrA and RfrB in iron homeostasis and interaction with host cells

Phenotypic Characterization of Salmonella RyhB-1 Mutations that Modulate Target Regulation

Genetics of CRISPR arrays in Salmonella Typhimurium 14028 associated with foreign DNA decay

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