Small RNAs in major foodborne pathogens: from novel regulatory activities to future applications

Thorsing, Mette; Santos, Patricia Isabel Teixeira dos; Kallipolitis, Birgitte H.

doi:10.1016/j.copbio.2017.08.006

Cited by 11 publications

(8 citation statements)

References 59 publications

(36 reference statements)

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“…The LhrC family in L. monocytogenes consists of seven sibling sRNAs with regulatory roles under infection-relevant conditions ( Thorsing et al, 2017 ). The family includes the highly homologous sRNAs LhrC1–5, as well as Rli22 and Rli33-1, which share lower homology.…”

Section: Introductionmentioning

confidence: 99%

The Small Regulatory RNAs LhrC1–5 Contribute to the Response of Listeria monocytogenes to Heme Toxicity

et al. 2018

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The LhrC family of small regulatory RNAs (sRNAs) is known to be induced when the foodborne pathogen Listeria monocytogenes is exposed to infection-relevant conditions, such as human blood. Here we demonstrate that excess heme, the core component of hemoglobin in blood, leads to a strong induction of the LhrC family members LhrC1–5. The heme-dependent activation of lhrC1–5 relies on the response regulator LisR, which is known to play a role in virulence and stress tolerance. Importantly, our studies revealed that LhrC1–5 and LisR contribute to the adaptation of L. monocytogenes to excess heme. Regarding the regulatory function of the sRNAs, we demonstrate that LhrC1–5 act to down-regulate the expression of known LhrC target genes under heme-rich conditions: oppA, tcsA, and lapB, encoding surface exposed proteins with virulence functions. These genes were originally identified as targets for LhrC-mediated control under cell envelope stress conditions, suggesting a link between the response to heme toxicity and cell envelope stress in L. monocytogenes. We also investigated the role of LhrC1–5 in controlling the expression of genes involved in heme uptake and utilization: lmo2186 and lmo2185, encoding the heme-binding proteins Hbp1 and Hbp2, respectively, and lmo0484, encoding a heme oxygenase-like protein. Using in vitro binding assays, we demonstrated that the LhrC family member LhrC4 interacts with mRNAs encoded from lmo2186, lmo2185, and lmo0484. For lmo0484, we furthermore show that LhrC4 uses a CU-rich loop for basepairing to the AG-rich Shine–Dalgarno region of the mRNA. The presence of a link between the response to heme toxicity and cell envelope stress was further underlined by the observation that LhrC1–5 down-regulate the expression of lmo0484 in response to the cell wall-acting antibiotic cefuroxime. Collectively, this study suggests a role for the LisR-regulated sRNAs LhrC1–5 in a coordinated response to excess heme and cell envelope stress in L. monocytogenes.

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Section: Introductionmentioning

confidence: 99%

The Small Regulatory RNAs LhrC1–5 Contribute to the Response of Listeria monocytogenes to Heme Toxicity

et al. 2018

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“…The experiment was performed three times with similar results. and translational repression, followed by degradation of the naked mRNA [1][2][3]5]. For instance, all members of the LhrC family of sRNAs (LhrC1-5, Rli22, and Rli33-1) canonically repress OppA expression by directly base pairing to the RBS, leading to decreased translation and stability of the oppA mRNA [12,13] (illustrated in Figure 7).…”

Section: Discussionmentioning

confidence: 99%

“…The LhrCs usually interact with target mRNAs through one or more UCCC-motifs located within single-stranded CU-rich regions [5]. The secondary structure of the LhrC family Figure 1.…”

Section: Lhrc4 Binds To a Region Located Far Upstream Of The Rbs In Tmentioning

confidence: 99%

“…In Gram-negative bacteria, Hfq is known to play a critical role in sRNA-mediated control, whereas in Gram-positive bacteria, Hfq-dependent sRNAs seem to be extremely rare [4]. Indeed, only a single well-characterized example is known in Gram-positive bacteria: the Hfq-dependent sRNA LhrA of the human pathogen Listeria monocytogenes (reviewed in [5]). L. monocytogenes is a facultative intracellular pathogen and the causative agent of the life-threatening foodborne disease listeriosis [6,7].…”

Section: Introductionmentioning

confidence: 99%

“…Additional studies in L. monocytogenes showed that the Hfqbinding sRNA LhrC also acts by direct base pairing to the RBS of partner mRNAs, but no role for Hfq has been found so far in controlling the stability or regulatory activities of LhrC [8,[11][12][13]. LhrC is a multicopy sRNA and the LhrC family comprises seven siblings: LhrC1-5, Rli22 and Rli33-1 (reviewed in [5]). Members of this family are highly induced under infection-relevant conditions, such as intracellular replication in macrophage cells (LhrC1-5, Rli33-1), whole human blood (all seven members), the intestinal lumen of mice (Rli22), and upon exposure to cell wall-acting antibiotics such as cefuroxime (LhrC1-5, Rli22) [11,14,15].…”

Section: Introductionmentioning

confidence: 99%

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The LhrC sRNAs control expression of T cell-stimulating antigen TcsA in Listeria monocytogenes by decreasing tcsA mRNA stability

et al. 2019

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The bacterial pathogen Listeria monocytogenes encodes seven homologous small regulatory RNAs, named the LhrC family of sRNAs. The LhrCs are highly induced under infection-relevant conditions and are known to inhibit the expression of multiple target mRNAs encoding virulence-associated surface proteins. In all cases studied so far, the LhrCs use their CU-rich regions for base pairing to complementary AG-rich sequences of the ribosomal binding site (RBS) of specific target mRNAs. Consequently, LhrC-mRNA interaction results in inhibition of translation followed by mRNA degradation, corresponding to the canonical model for sRNA-mediated gene regulation in bacteria. Here, we demonstrate that the LhrC sRNAs employ a different regulatory mechanism when acting to down-regulate the expression of tcsA, encoding a T cell-stimulating antigen. In this case, LhrC base pairs to an AG-rich site located well upstream of the RBS in tcsA mRNA. Using an in vitro translation assay, we found that LhrC could not prevent the ribosome from translating the tcsA messenger. Rather, the LhrC sRNAs act to decrease the half-life of tcsA mRNA in vivo. Importantly, LhrC-mediated destabilization of tcsA mRNA relies on an intact LhrC binding site near the 5´-end of the tcsA mRNA and occurs independently of translation. Based on these findings, we propose an alternative mechanism for LhrC-mediated control in L. monocytogenes that relies solely on sRNA-induced degradation of a target mRNA.

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Experimental Validation of RNA–RNA Interactions by Electrophoretic Mobility Shift Assay

Lillebæk,

Kallipolitis

2024

Methods in Molecular Biology

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Small RNAs in major foodborne pathogens: from novel regulatory activities to future applications

Cited by 11 publications

References 59 publications

The Small Regulatory RNAs LhrC1–5 Contribute to the Response of Listeria monocytogenes to Heme Toxicity

The Small Regulatory RNAs LhrC1–5 Contribute to the Response of Listeria monocytogenes to Heme Toxicity

The LhrC sRNAs control expression of T cell-stimulating antigen TcsA in Listeria monocytogenes by decreasing tcsA mRNA stability

Experimental Validation of RNA–RNA Interactions by Electrophoretic Mobility Shift Assay

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