The insecticidal toxin genes of <i><scp>Y</scp>ersinia enterocolitica</i> are activated by the thermolabile <scp>LTTR</scp>‐like regulator <scp>TcaR</scp>2 at low temperatures

Starke, Mandy; Richter, Marleen; Fuchs, Thilo M.

doi:10.1111/mmi.12296

Cited by 21 publications

(32 citation statements)

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“…We focus on examples of how microbes sense the elevated temperatures once they enter a mammalian host, even though pathogens of plants and insects can regulate gene expression in response to lower temperatures. [2][3][4] Mechanisms of thermo-sensing: exerting multi-level control Regulation at the level of DNA Changes in the local temperature are detected by bacteria through multiple mechanisms; temperature can influence the topology of DNA, affect RNA structuring and metabolism, and change the activity and processing of proteins ( Fig. 2).…”

Section: Introductionmentioning

confidence: 99%

Thermal control of virulence factors in bacteria: A hot topic

2014

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Pathogenic bacteria sense environmental cues, including the local temperature, to control the production of key virulence factors. Thermal regulation can be achieved at the level of DNA, RNA or protein and although many virulence factors are subject to thermal regulation, the exact mechanisms of control are yet to be elucidated in many instances. Understanding how virulence factors are regulated by temperature presents a significant challenge, as gene expression and protein production are often influenced by complex regulatory networks involving multiple transcription factors in bacteria. Here we highlight some recent insights into thermal regulation of virulence in pathogenic bacteria. We focus on bacteria which cause disease in mammalian hosts, which are at a significantly higher temperature than the outside environment. We outline the mechanisms of thermal regulation and how understanding this fundamental aspect of the biology of bacteria has implications for pathogenesis and human health.

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Section: Introductionmentioning

confidence: 99%

Thermal control of virulence factors in bacteria: A hot topic

2014

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“…A) between the homologous of YE1612 and YE1611 (Fuchs et al ., ), and was included in this analysis by a similar construct. The corresponding constructs in W22703 with the exception of the P tcaB :: lux and P tccC2 :: lux fusions constructed here were already investigated (Starke et al ., ) and served as references. To analyse tcaA , ymoA was deleted in strain W22703 tcaA (134):: lux .…”

Section: Resultsmentioning

confidence: 99%

“…An approximately 10‐fold and 8‐fold increase of tcaB transcription upon ymoA deletion was detected at 15°C and 37°C, respectively. Interestingly, the promoter of tcaC , for which no transcription had been detected so far (Starke et al ., ), responded to the deletion of ymoA at 15°C (4.0 × 10 4 RLU/OD 600 ). The tccC1 promoter is silent at 15°C and only slightly active at body temperature during growth in LB medium, but was induced upon ymoA deletion at both 15°C (3.8 × 10 4 RLU/OD 600 ) and 37°C (7.6 × 10 4 cRLU/OD 600 ).…”

Section: Resultsmentioning

confidence: 99%

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YmoA negatively controls the expression of insecticidal genes in Yersinia enterocolitica

Starke

Fuchs

2014

Molecular Microbiology

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SummaryYersinia enterocolitica is toxic towards invertebrates due to the presence of the toxin complex (tc) genes that are activated by the thermolabile regulator TcaR2. In the search for further regulatory factors involved in insecticidal gene expression, the modulator of yersinial virulence, YmoA, was identified to silence all tc genes of the Y. enterocolitica strain W22703 (biovar 2, serovar O:9). Using promoter fusions with the luciferase reporter, we found that the deletion of ymoA results in elevated transcription of tcaR1, tcaR2, tcaA, tcaB, tcaC, tccC1 and tccC2 at both 15°C and 37°C. Complementation by episomal ymoA significantly reduced tc gene expression, thus validating the inhibitory activity of YmoA on the production of insecticidal proteins. YmoA contributes to the binding properties of H-NS to the tc promoters by forming a complex with this nucleoid-associated protein, and this complex not only binds to the upstream regions of all tc genes, but also to intragenic sites of tcaA and tcaB that play an important role in controlling the expression of both genes. At low temperature, the intracellular amount of thermostable YmoA is not reduced, but the repressor is less functional. These data point to H-NS/YmoA as an antagonist of the inducer TcaR2.

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“…Transcriptional organization of the lysis gene cassette. The transcriptional activity of the promoter of the lysis cassette is very low (unpublished data) and below a threshold value defined recently (15). We revealed the transcriptional organization of this lysis cassette using reverse transcriptase PCR with RNA isolated from strain W22703 grown at 15°C to an optical density at 600 nm (OD 600 ) of 0.85. cDNA of 12 regions spanning approximately 200 to 800 bp was analyzed ( Fig.…”

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Activity of a Holin-Endolysin System in the Insecticidal Pathogenicity Island of Yersinia enterocolitica

et al. 2018

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is a pathogen that causes gastroenteritis in humans. Because of its low-temperature-dependent insecticidal activity, it can oscillate between invertebrates and mammals as host organisms. The insecticidal activity of strain W22703 is associated with a pathogenicity island of 19 kb (Tc-PAI ), which carries regulators and genes encoding the toxin complex (Tc). The island also harbors four phage-related and highly conserved genes of unknown functions, which are polycistronically transcribed. Two open reading frames showed significant homologies to holins and endolysins and exhibited lytic activity in cells upon overexpression. When a set of strains was tested in an equivalent manner, highly diverse susceptibilities to lysis were observed, and some strains were resistant to lysis. If cell lysis occurred (as demonstrated by membrane staining), it was more pronounced when two accessory elements of the cassette coding for an i-spanin and an o-spanin were included in the overexpression construct. The pore-forming function of the putative holin, HolY, was demonstrated by complementation of the lysis defect of a phage λ S holin mutant. In experiments performed with membrane preparations, ElyY exhibited high specificity for W22703 peptidoglycan, with a cleavage activity resembling that of lysozyme. Although the functionality of the lysis cassette from Tc-PAI was demonstrated in this study, its biological role remains to be elucidated. The knowledge of how pathogens survive in the environment is pivotal for our understanding of bacterial virulence. The insecticidal and nematocidal activity of spp., by which the bacteria gain access to nutrients and thus improve their environmental fitness, is conferred by the toxin complex (Tc) encoded on a highly conserved pathogenicity island termed Tc-PAI While the regulators and the toxin subunits of the island had been characterized in some detail, the role of phage-related genes within the island remained to be elucidated. Here, we demonstrate that this cassette encodes a holin, an endolysin, and two spanins that, at least upon overexpression, lyse strains.

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The insecticidal toxin genes of Yersinia enterocolitica are activated by the thermolabile LTTR‐like regulator TcaR2 at low temperatures

Cited by 21 publications

References 71 publications

Thermal control of virulence factors in bacteria: A hot topic

Thermal control of virulence factors in bacteria: A hot topic

YmoA negatively controls the expression of insecticidal genes in Yersinia enterocolitica

Activity of a Holin-Endolysin System in the Insecticidal Pathogenicity Island of Yersinia enterocolitica

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