The Transcriptional Regulator Lrp Contributes to Toxin Expression, Sporulation, and Swimming Motility in Clostridium difficile

Chen, Kuan‐Yu; Rathod, Jagat; Chiu, Yi-Ching; Chen, Jenn Wei; Tsai, Pei-Jane; Huang, I-Hsiu

doi:10.3389/fcimb.2019.00356

Cited by 18 publications

(13 citation statements)

References 68 publications

(93 reference statements)

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“…difficile strains are known to have diverse phenotypes both in culture and during infection. These strain-specific properties can be driven by a variety of factors, including altered genomic content [55] or variable gene expression patterns [56, 57]. To address the latter possibility, the transcriptomes of C.…”

Section: Resultsmentioning

confidence: 99%

Clostridioides difficile strain-dependent and strain-independent adaptations to a microaerobic environment

et al. 2021

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Clostridioides difficile (formerly Clostridium difficile ) colonizes the gastrointestinal tract following disruption of the microbiota and can initiate a spectrum of clinical manifestations ranging from asymptomatic to life-threatening colitis. Following antibiotic treatment, luminal oxygen concentrations increase, exposing gut microbes to potentially toxic reactive oxygen species. Though typically regarded as a strict anaerobe, C. difficile can grow at low oxygen concentrations. How this bacterium adapts to a microaerobic environment and whether those responses to oxygen are conserved amongst strains is not entirely understood. Here, two C. difficile strains (630 and CD196) were cultured in 1.5% oxygen and the transcriptional response to long-term oxygen exposure was evaluated via RNA-sequencing. During growth in a microaerobic environment, several genes predicted to protect against oxidative stress were upregulated, including those for rubrerythrins and rubredoxins. Transcription of genes involved in metal homeostasis was also positively correlated with increased oxygen levels and these genes were amongst the most differentially transcribed. To directly compare the transcriptional landscape between C. difficile strains, a ‘consensus-genome’ was generated. On the basis of the identified conserved genes, basal transcriptional differences as well as variations in the response to oxygen were evaluated. While several responses were similar between the strains, there were significant differences in the abundance of transcripts involved in amino acid and carbohydrate metabolism. Furthermore, intracellular metal concentrations significantly varied both in an oxygen-dependent and oxygen-independent manner. Overall, these results indicate that C. difficile adapts to grow in a low oxygen environment through transcriptional changes, though the specific strategy employed varies between strains.

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Section: Resultsmentioning

confidence: 99%

Clostridioides difficile strain-dependent and strain-independent adaptations to a microaerobic environment

et al. 2021

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“…The C. difficile genome [45] and laboratory strain variants (for example, strain 630Δerm [46]) are also highly AT-rich with 71% AT content, consistent with the recent findings [13] that the BBZ compounds BBZ5 and ridinilazole could have genomic DNA minor groove binding as their primary mode of action. Exact analogues of appY in C. difficile have not yet been established but several transcriptional regulators of toxin production in this organism have been identified such as RstA [47] and Lrp [48]. The latter gene, lrp, also has high AT content (67%: https://clostridium.biocyc.org/).…”

Section: Dna Binding and Potential Relevance To C Difficile Mode Of A...mentioning

confidence: 99%

The mechanism of resistance in Escherichia coli to ridinilazole and other antibacterial head-to-head bis-benzimidazole compounds

et al. 2022

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The appY gene has been characterised as conferring resistance to a novel series of antimicrobial benzimidazole derivatives in E. coli MC1061 cells when expressed in high copy-number. A microarray approach was used to identify genes involved in the mechanism of appY-mediated antibacterial resistance, that were up- or down-regulated following induction of the gene in the appY knockout strain JW0553. In total, expression of 90 genes was induced and 48 repressed greater than 2.5-fold (P < 0.05), 45 min after appY induction. Over half the genes up-regulated following appY expression had confirmed or putative roles in acid resistance (AR) and response to oxidative and antibiotic stresses. These included the genes for MdtE and MdtF, which form a multi-drug transporter with TolC and have been implicated in resistance to several antibiotics including erythromycin. Amongst the acid resistance genes were gadAB and adiAC encoding the glutamate-dependant (AR2) and arginine-dependant (AR3) acid resistance systems respectively, in addition to the transcriptional activators of these systems gadE and gadX. In agreement with earlier studies, appA, appCB and hyaA-F were also up-regulated following induction of appY. This study has also confirmed that over-expression of mdtEF confers resistance to these antibacterial benzimidazoles, indicating that the observation of appY conferring resistance to these compounds, proceeds through an appY-mediated up-regulation of this efflux transporter. To assess the importance of the AppY enzyme to acid stress responses, the percentage survival of bacteria in acidified media (pH ≤ 2) was measured. From an initial input of 1 × 106 CFU/ml, the wild-type strain MG1655 showed 7.29% and 0.46% survival after 2 and 4 h, respectively. In contrast, strain JW0553 in which appY is deleted was completely killed by the treatment. Transformation of JW0553 with a plasmid carrying appY returned survival to wild-type levels (7.85% and 1.03% survival at 2 and 4 h). Further dissection of the response by prior induction of each of the three AR systems has revealed that AR1 and AR3 were most affected by the absence of appY. This work highlights an important and previously unidentified role for the AppY enzyme in mediating the responses to several stress conditions. It is likely that the appY gene fits into a complex transcriptional regulatory network involving σS and gadE and gadX. Further work to pinpoint its position in such a hierarchy and to assess the contribution of appY to oxidative stress responses should help determine its full significance. This work is also consistent with recent studies in C. difficile showing that the mechanism of action of ridinilazole involves AT-rich DNA minor groove binding.

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“…Members of this family coordinate PAMP responses, activating phosphorylation cascades and stimulating defense de-repression in plants ( Peng et al, 2008 ; Chen et al, 2019 ). They also mediate the induction of callose synthase genes as well as jasmonate and salicylic acid biosynthesis in plants reacting against Pseudomonas syringae infection ( Peng et al, 2008 ; Park and Ronald, 2012 ; Chen et al, 2019 ). Citrus plants encode more than 50 WRKY factors ( Vives-Peris et al, 2018 ) in their genomes.…”

Section: Discussionmentioning

confidence: 99%

‘Candidatus Liberibacter asiaticus’ Multimeric LotP Mediates Citrus sinensis Defense Response Activation

et al. 2021

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‘Candidatus Liberibacter asiaticus’ is known as the most pathogenic organism associated with citrus greening disease. Since its publicized emergence in Florida in 2005, ‘Ca. L. asiaticus’ remains unculturable. Currently, a limited number of potential disease effectors have been identified through in silico analysis. Therefore, these potential effectors remain poorly characterized and do not fully explain the complexity of symptoms observed in citrus trees infected with ‘Ca. L. asiaticus.’ LotP has been identified as a potential effector and have been partially characterized. This protein retains structural homology to the substrate binding domain of the Lon protease. LotP interacts with chaperones like GroEL, Hsp40, DnaJ, and ClpX and may exercise its biological role through interactions with different proteins involved in proteostasis networks. Here, we evaluate the interactome of LotP—revealing a new protein–protein interaction target (Lon-serine protease) and its effect on citrus plant tissue integrity. We found that via protein–protein interactions, LotP can enhance Lon protease activity, increasing the degradation rate of its specific targets. Infiltration of purified LotP strained citrus plant tissue causing photoinhibition and chlorosis after several days. Proteomics analysis of LotP tissues recovering after the infiltration revealed a large abundance of plant proteins associated with the stabilization and processing of mRNA transcripts, a subset of important transcription factors; and pathways associated with innate plant defense were highly expressed. Furthermore, interactions and substrate binding module of LotP suggest potential interactions with plant proteins, most likely proteases.

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The Transcriptional Regulator Lrp Contributes to Toxin Expression, Sporulation, and Swimming Motility in Clostridium difficile

Cited by 18 publications

References 68 publications

Clostridioides difficile strain-dependent and strain-independent adaptations to a microaerobic environment

Clostridioides difficile strain-dependent and strain-independent adaptations to a microaerobic environment

The mechanism of resistance in Escherichia coli to ridinilazole and other antibacterial head-to-head bis-benzimidazole compounds

‘Candidatus Liberibacter asiaticus’ Multimeric LotP Mediates Citrus sinensis Defense Response Activation

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