Small regulatory RNAs in Streptococcus pneumoniae: discovery and biological functions

Wilton, Joana; Acebo, Paloma; Herranz, Cristina; Estacio-Gómez, Alicia; Amblar, Mónica

doi:10.3389/fgene.2015.00126

Cited by 15 publications

(13 citation statements)

References 49 publications

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“…Although the pneumococcus expresses a great number of sRNAs with evidence for important physiological roles (Mann et al , ; Laux et al , ; Wilton et al , ), homologs of CsrA, Hfq, or ProQ are not present in this organism (Tettelin et al , ). A preliminary prediction from our cluster analysis and subsequent protein co‐purification experiments is that S. pneumoniae perhaps does not possess a general RBP analogous to Hfq or ProQ, the two RBPs that together associate with > 80% of the sRNAs in E. coli and Salmonella (Holmqvist & Vogel, ).…”

Section: Discussionmentioning

confidence: 99%

Grad‐seq in a Gram‐positive bacterium reveals exonucleolytic sRNA activation in competence control

et al. 2020

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RNA-protein interactions are the crucial basis for many steps of bacterial gene expression, including post-transcriptional control by small regulatory RNAs (sRNAs). In stark contrast to recent progress in the analysis of Gram-negative bacteria, knowledge about RNAprotein complexes in Gram-positive species remains scarce. Here, we used the Grad-seq approach to draft a comprehensive landscape of such complexes in Streptococcus pneumoniae, in total determining the sedimentation profiles of~88% of the transcripts and~62% of the proteins of this important human pathogen. Analysis of in-gradient distributions and subsequent tag-based protein capture identified interactions of the exoribonuclease Cbf1/YhaM with sRNAs that control bacterial competence for DNA uptake. Unexpectedly, the nucleolytic activity of Cbf1 stabilizes these sRNAs, thereby promoting their function as repressors of competence. Overall, these results provide the first RNA/protein complexome resource of a Gram-positive species and illustrate how this can be utilized to identify new molecular factors with functions in RNA-based regulation of virulence-relevant pathways.

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Section: Discussionmentioning

confidence: 99%

Grad‐seq in a Gram‐positive bacterium reveals exonucleolytic sRNA activation in competence control

et al. 2020

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“…Expression of tmRNA in the pneumococcus was recently demonstrated (Kumar et al, 2010; Acebo et al, 2012; Mann et al, 2012; Wilton et al, 2015) and, although no functional studies have been reported so far, its deficiency has strong effects in pathogenesis. In fact, ssrA inactivation reduced the ability to adhere and to invade endothelial cells, reduced the fitness and competitive index in lungs and causes attenuation in invasive diseases upon intranasal challenge (Mann et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Absence of tmRNA Has a Protective Effect against Fluoroquinolones in Streptococcus pneumoniae

et al. 2017

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The transfer messenger RNA (tmRNA), encoded by the ssrA gene, is a small non-coding RNA involved in trans-translation that contributes to the recycling of ribosomes stalled on aberrant mRNAs. In most bacteria, its inactivation has been related to a decreased ability to respond to and recover from a variety of stress conditions. In this report, we investigated the role of tmRNA in stress adaptation in the human pathogen Streptococcus pneumoniae. We constructed a tmRNA deletion mutant and analyzed its response to several lethal stresses. The ΔssrA strain grew slower than the wild type, indicating that, although not essential, tmRNA is important for normal pneumococcal growth. Moreover, deletion of tmRNA increased susceptibility to UV irradiation, to exogenous hydrogen peroxide and to antibiotics that inhibit protein synthesis and transcription. However, the ΔssrA strain was more resistant to fluoroquinolones, showing twofold higher MIC values and up to 1000-fold higher survival rates than the wild type. Deletion of SmpB, the other partner in trans-translation, also reduced survival to levofloxacin in a similar extent. Accumulation of intracellular reactive oxygen species associated to moxifloxacin and levofloxacin treatment was also highly reduced (∼100-fold). Nevertheless, the ΔssrA strain showed higher intracellular accumulation of ethidium bromide and levofloxacin than the wild type, suggesting that tmRNA deficiency protects pneumococcal cells from fluoroquinolone-mediated killing. In fact, analysis of chromosome integrity revealed that deletion of tmRNA prevented the fragmentation of the chromosome associated to levofloxacin treatment. Moreover, such protective effect appears to relay mainly on inhibition of protein synthesis, since a similar effect was observed with antibiotics that inhibit that process. The emergence and spread of drug-resistant pneumococci is a matter of concern and these results contribute to a better comprehension of the mechanisms underlying fluoroquinolones action.

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“…Because SdbA is required for disulfide bond formation (26), CiaRH might respond to general stress created by misfolding of SdbA substrates or by the loss of function of a specific SdbA substrate. Bacteria sense envelope stress by using two-component systems, and thiol-disulfide oxidoreductases have been linked to these stress responses in both Gram-negative and Gram-positive species (61)(62)(63)(64). For example, Bacillus subtilis senses envelope stress by using a system called CssRS, which, like CiaRH in streptococci, regulates expression of the DegP-family proteases HtrA and HtrB (65,66).…”

Section: Figmentioning

confidence: 99%

Mutation of the Thiol-Disulfide Oxidoreductase SdbA Activates the CiaRH Two-Component System, Leading to Bacteriocin Expression Shutdown in Streptococcus gordonii

2016

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Streptococcus gordonii is a commensal inhabitant of the human oral cavity. To maintain its presence as a major component of oral biofilms, S. gordonii secretes inhibitory molecules such as hydrogen peroxide and bacteriocins to inhibit competitors. S. gordonii produces two nonmodified bacteriocins (i.e., Sth 1 and Sth 2 ) that are regulated by the Com two-component regulatory system, which also regulates genetic competence. Previously we found that the thiol-disulfide oxidoreductase SdbA was required for bacteriocin activity; however, the role of SdbA in Com signaling was not clear. Here we demonstrate that ⌬sdbA mutants lacked bacteriocin activity because the bacteriocin gene sthA was strongly repressed and the peptides were not secreted. Addition of synthetic competence-stimulating peptide to the medium reversed the phenotype, indicating that the Com pathway was functional but was not activated in the ⌬sdbA mutant. Repression of bacteriocin production was mediated by the CiaRH two-component system, which was strongly upregulated in the ⌬sdbA mutant, and inactivation of CiaRH restored bacteriocin production. The CiaRH-induced protease DegP was also upregulated in the ⌬sdbA mutant, although it was not required for inhibition of bacteriocin production. This establishes CiaRH as a regulator of Sth bacteriocin activity and links the CiaRH and Com systems in S. gordonii. It also suggests that either SdbA or one of its substrates is an important factor in regulating activation of the CiaRH system. IMPORTANCEStreptococcus gordonii is a noncariogenic colonizer of the human oral cavity. To be competitive in the oral biofilm, S. gordonii secretes antimicrobial peptides called bacteriocins, which inhibit closely related species. Our previous data showed that mutation of the disulfide oxidoreductase SdbA abolished bacteriocin production. In this study, we show that mutation of SdbA generates a signal that upregulates the CiaRH two-component system, which in turn downregulates a second two-component system, Com, which regulates bacteriocin expression. Our data show that these systems are also linked in S. gordonii, and the data reveal that the cell's ability to form disulfide bonds is sensed by the CiaRH system. O ral biofilms are highly competitive, constantly fluctuating environments. The bacteria that colonize this niche contend with a high density of competing bacteria of an estimated 2,000 different taxa and dramatic environmental changes that are dependent on host behavior (1, 2). Streptococcus gordonii is a pioneer colonizer of this environment, where it initiates biofilm formation by binding directly to the acquired salivary pellicle on the tooth surface (2, 3). Once established, S. gordonii persists within the host as part of the oral microbiota. The presence of S. gordonii is associated with oral health (4, 5), and it has been shown to inhibit biofilm formation by cariogenic species (6, 7).S. gordonii uses several strategies to gain advantage over its competitors and to colonize the oral cavity successfully...

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Small regulatory RNAs in Streptococcus pneumoniae: discovery and biological functions

Cited by 15 publications

References 49 publications

Grad‐seq in a Gram‐positive bacterium reveals exonucleolytic sRNA activation in competence control

Grad‐seq in a Gram‐positive bacterium reveals exonucleolytic sRNA activation in competence control

Absence of tmRNA Has a Protective Effect against Fluoroquinolones in Streptococcus pneumoniae

Mutation of the Thiol-Disulfide Oxidoreductase SdbA Activates the CiaRH Two-Component System, Leading to Bacteriocin Expression Shutdown in Streptococcus gordonii

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