The blue-light receptor YtvA from Bacillus subtilis is permanently incorporated into the stressosome independent of the illumination state

Jurk, Marcel; Schramm, Philipp; Schmieder, Peter

doi:10.1016/j.bbrc.2013.02.025

Cited by 19 publications

(26 citation statements)

References 28 publications

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“…1). In contrast to the related RsbR co-antagonists, YtvA by itself does not appear capable of forming a stressosome with RsbS in vitro [37] and is only known to have a positive signaling role [11], [14], [15], [38]. Nonetheless, if its LOV domain were capable of redox as well as blue-light sensing, YtvA is a candidate for an S59-independent route of signaling, possibly detecting the secondary oxidative stress elicited by ethanol challenge [39].…”

Section: Resultsmentioning

confidence: 96%

Genetic Evidence for a Phosphorylation-Independent Signal Transduction Mechanism within the Bacillus subtilis Stressosome

Gaidenko

Price

2014

PLoS ONE

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The stressosome is a 1.8 MDa cytoplasmic complex that controls diverse bacterial signaling pathways. Its role is best understood in Bacillus subtilis, where it activates the σB transcription factor in response to a variety of sharp environmental challenges, including acid, ethanol, heat or salt stress. However, details of the signaling mechanism within the stressosome remain uncertain. The core of the complex comprises one or more members of the RsbR co-antagonist family together with the RsbS antagonist protein, which binds the RsbT kinase in the absence of stress. As part of the response, RsbT first phosphorylates the RsbRA co-antagonist on T171 and then RsbS on S59; this latter event correlates with the stress-induced release of RsbT to activate downstream signaling. Here we examine the in vivo consequence of S59 phosphorylation in a model strain whose stressosome core is formed solely with the RsbRA co-antagonist and RsbS. A phosphorylation-deficient S59A substitution in RsbS blocked response to mild stress but had declining impact as stress increased: with strong ethanol challenge response with S59A was 60% as robust as with wild type RsbS. Genetic analysis narrowed this S59-independent activation to the stressosome and established that significant signaling still occurred in a strain bearing both the T171A and S59A substitutions. We infer that S59 phosphorylation increases signaling efficiency but is not essential, and that a second (or underlying) mechanism of signal transduction prevails in its absence. This interpretation nullifies models in which stressosome signaling is solely mediated by control of RsbT kinase activity toward S59.

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Section: Resultsmentioning

confidence: 96%

Genetic Evidence for a Phosphorylation-Independent Signal Transduction Mechanism within the Bacillus subtilis Stressosome

Gaidenko

Price

2014

PLoS ONE

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“…The results obtained were in general agreement with the earlier biochemical studies with respect to the number of RsbR proteins. In addition, it was shown that YtvA can form an integral part of stressosomes (see further below).…”

Section: The Environmental Branch Of the Gsr And The Functioning Of “mentioning

confidence: 99%

“…Nevertheless, YtvA does carry out its function as a blue‐light photoreceptor for the GSR as an integral part of the stressosomes . Using fluorescence microscopy, it was shown that YtvA localizes in spots that correspond to stressosomes in the presence of RsbRA, but that YtvA is diffusely localized with RsbRB as the only RsbR protein present .…”

Section: Ytva: a Blue‐light Photoreceptor Of The Gsrmentioning

confidence: 99%

Activation of the General Stress Response of Bacillus subtilis by Visible Light

Steen

Hellingwerf

2015

Photochem & Photobiology

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A key challenge for microbiology is to understand how evolution has shaped the wiring of regulatory networks. This is amplified by the paucity of information of power-spectra of physicochemical stimuli to which microorganisms are exposed. Future studies of genome evolution, driven by altered stimulus regimes, will therefore require a versatile signal transduction system that allows accurate signal dosing. Here, we review the general stress response of Bacillus subtilis, and its upstream signal transduction network, as a candidate system. It can be activated by red and blue light, and by many additional stimuli. Signal integration therefore is an intricate function of this system. The blue-light response is elicited via the photoreceptor YtvA, which forms an integral part of stressosomes, to activate expression of the stress regulon of B. subtilis. Signal transfer through this network can be assayed with reporter enzymes, while intermediate steps can be studied with live-cell imaging of fluorescently tagged proteins. Different parts of this system have been studied in vitro, such that its computational modeling has made significant progress. One can directly relate the microscopic characteristics of YtvA with activation of the general stress regulon, making this system a very well-suited system for network evolution studies.

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“…Within Bacillus subtilis , a light sensing protein YtvA has been discovered (Losi et al, 2002; Avila-Perez et al, 2006, 2009). This protein is present in a stress sensing complex known as the stressosome which is composed of the proteins RsbR and its paralogs as well as RsbS and RsbT ( Figure 2 ; Gaidenko et al, 1999; Kim et al, 2004b; Hecker et al, 2007; Marles-Wright et al, 2008; Jurk et al, 2013). The stress signals are thought to be sensed by the protruding N- termini of these sensory proteins and are transduced into the core of the stressosome (Marles-Wright et al, 2008).…”

Section: Stresses Encountered In Foodmentioning

confidence: 99%

The Role of Stress and Stress Adaptations in Determining the Fate of the Bacterial Pathogen Listeria monocytogenes in the Food Chain

2016

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The foodborne pathogen Listeria monocytogenes is a highly adaptable organism that can persist in a wide range of environmental and food-related niches. The consumption of contaminated ready-to-eat foods can cause infections, termed listeriosis, in vulnerable humans, particularly those with weakened immune systems. Although these infections are comparatively rare they are associated with high mortality rates and therefore this pathogen has a significant impact on food safety. L. monocytogenes can adapt to and survive a wide range of stress conditions including low pH, low water activity, and low temperature, which makes it problematic for food producers who rely on these stresses for preservation. Stress tolerance in L. monocytogenes can be explained partially by the presence of the general stress response (GSR), a transcriptional response under the control of the alternative sigma factor sigma B (σB) that reconfigures gene transcription to provide homeostatic and protective functions to cope with the stress. Within the host σB also plays a key role in surviving the harsh conditions found in the gastrointestinal tract. As the infection progresses beyond the GI tract L. monocytogenes uses an intracellular infectious cycle to propagate, spread and remain protected from the host’s humoral immunity. Many of the virulence genes that facilitate this infectious cycle are under the control of a master transcriptional regulator called PrfA. In this review we consider the environmental reservoirs that enable L. monocytogenes to gain access to the food chain and discuss the stresses that the pathogen must overcome to survive and grow in these environments. The overlap that exists between stress tolerance and virulence is described. We review the principal measures that are used to control the pathogen and point to exciting new approaches that might provide improved means of control in the future.

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The blue-light receptor YtvA from Bacillus subtilis is permanently incorporated into the stressosome independent of the illumination state

Cited by 19 publications

References 28 publications

Genetic Evidence for a Phosphorylation-Independent Signal Transduction Mechanism within the Bacillus subtilis Stressosome

Genetic Evidence for a Phosphorylation-Independent Signal Transduction Mechanism within the Bacillus subtilis Stressosome

Activation of the General Stress Response of Bacillus subtilis by Visible Light

The Role of Stress and Stress Adaptations in Determining the Fate of the Bacterial Pathogen Listeria monocytogenes in the Food Chain

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