Transcriptional and Post-transcriptional Regulatory Mechanisms Controlling Type III Secretion

Volk, Marcel; Vollmer, Ines; Heroven, Ann Kathrin; Dersch, Petra

doi:10.1007/82_2019_168

Cited by 6 publications

(8 citation statements)

References 89 publications

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“…D) Transcript levels of sctG and virF at ODin 1.5 vs. 0.1, as measured by reverse transcriptase quantitative PCR (see panel A). E) Schematic depiction of the influence of the CsrABC system on VirF production [24,47,67]. The regulatory RNAs csrB and csrC sequester CsrA, preventing it from binding and stabilizing the virF transcript.…”

Section: Resultsmentioning

confidence: 99%

Yersiniaactively downregulates type III secretion and adhesion at higher cell densities

Ermoli,

Spahn,

Glatter

et al. 2024

Preprint

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The T3SS injectisome is used by Gram-negative bacteria, including important pathogens, to manipulate eukaryotic target cells by injecting effector proteins. Some bacterial species display bimodal expression of the T3SS, allowing the T3SS-negative population to benefit from the activity of their T3SS-positive siblings without investing in the assembly and production of injectisomes. In contrast,Yersinia enterocolitica, a main T3SS model organism that uses the system to evade the host immune response, was thought to uniformly express and assemble injectisomes, which are then activated by target cell contact. In this study, we found that at higher local bacterial concentrations,Yersiniaactively downregulates T3SS expression, assembly and activity. This effect is reversible, highly specific, and distinct from stationary phase adaptation. A key player is the main T3SS transcription factor VirF, which is downregulated at the higher cell densities suppressing T3SS activity and whosein transexpression restores T3SS expression and assembly. Transcript analysis showed that this effect is mediated by increased levels of the regulatory RNAscsrBC, which sequester the regulatory protein CsrA and destabilize thevirFtranscript. Downregulation of the VirF-dependent adhesin YadA led to a drastic reduction in bacterial cell adhesion. We propose that the phenotype described in this study, active downregulation of cell attachment and T3SS secretion at higher local bacterial densities, is a strategy implemented to promote bacterial replication and dissemination at later stages of infection.

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Section: Resultsmentioning

confidence: 99%

Yersiniaactively downregulates type III secretion and adhesion at higher cell densities

Ermoli,

Spahn,

Glatter

et al. 2024

Preprint

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“…Once the bacteria sense the right environmental signals, which vary among bacterial species, expression of the injectisome components is triggered. For example, in Yersinia , the host temperature of 37 °C activates the T3SS expression, whereas osmolarity, pH, and oxygen availability in the host intestinal environment serve as a trigger in Salmonella [83, 84]. Expression of the components leads to assembly of the injectisome complex to occur in about 30 min [19, 85].…”

Section: Translocatorsmentioning

confidence: 99%

Virulence-associated type III secretion systems in Gram-negative bacteria

2023

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Virulence-associated bacterial type III secretion systems are multiprotein molecular machines that promote the pathogenicity of bacteria towards eukaryotic host cells. These machines form needle-like structures, named injectisomes, that span both bacterial and host membranes, forming a direct conduit for the delivery of bacterial proteins into host cells. Once within the host, these bacterial effector proteins are capable of manipulating a multitude of host cell functions. In recent years, the knowledge of assembly, structure and function of these machines has grown substantially and is presented and discussed in this review.

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“…Some of the most important virulence properties are encoded on the virulence plasmid pYV (pIB1). They are predominantly expressed at 37°C upon contact with host immune cells after the bacteria entered the gut-associated lymphatic tissues ( Straley and Perry, 1995 ; Kusmierek et al, 2019 ; Volk et al, 2019 ; Schneiders et al, 2021 ). Among them are the adhesion factor YadA, the structural components of a functional type three secretion system (T3SS) and the antiphagocytic Yersinia outer proteins (Yops) - the effectors which are secreted and translocated by the T3S machinery ( Cornelis, 2006 ; Bliska et al, 2013 ).…”

Section: Introductionmentioning

confidence: 99%

The Small Protein YmoA Controls the Csr System and Adjusts Expression of Virulence-Relevant Traits of Yersinia pseudotuberculosis

et al. 2021

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Virulence gene expression of Yersinia pseudotuberculosis changes during the different stages of infection and this is tightly controlled by environmental cues. In this study, we show that the small protein YmoA, a member of the Hha family, is part of this process. It controls temperature- and nutrient-dependent early and later stage virulence genes in an opposing manner and co-regulates bacterial stress responses and metabolic functions. Our analysis further revealed that YmoA exerts this function by modulating the global post-transcriptional regulatory Csr system. YmoA pre-dominantly enhances the stability of the regulatory RNA CsrC. This involves a stabilizing stem-loop structure within the 5′-region of CsrC. YmoA-mediated CsrC stabilization depends on H-NS, but not on the RNA chaperone Hfq. YmoA-promoted reprogramming of the Csr system has severe consequences for the cell: we found that a mutant deficient of ymoA is strongly reduced in its ability to enter host cells and to disseminate to the Peyer’s patches, mesenteric lymph nodes, liver and spleen in mice. We propose a model in which YmoA controls transition from the initial colonization phase in the intestine toward the host defense phase important for the long-term establishment of the infection in underlying tissues.

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Transcriptional and Post-transcriptional Regulatory Mechanisms Controlling Type III Secretion

Cited by 6 publications

References 89 publications

Yersiniaactively downregulates type III secretion and adhesion at higher cell densities

Yersiniaactively downregulates type III secretion and adhesion at higher cell densities

Virulence-associated type III secretion systems in Gram-negative bacteria

The Small Protein YmoA Controls the Csr System and Adjusts Expression of Virulence-Relevant Traits of Yersinia pseudotuberculosis

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