kinC/D‐mediated heterogeneous expression of spo0A during logarithmical growth in Bacillus subtilis is responsible for partial suppression of φ29 development

Castilla-Llorente, Virginia; Salas, Margarita; Meijer, Wilfried J. J.

doi:10.1111/j.1365-2958.2008.06234.x

Cited by 15 publications

(19 citation statements)

References 57 publications

(101 reference statements)

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“…It is also in agreement with the finding that the overproduction of either KinA or KinC can markedly enhance the fraction of cells with polar septa, the formation of which requires the expression of high-threshold Spo0A-dependent genes (42). KinC and KinD are also known to be involved in a low level of phosphorylation of Spo0A during growth, sufficient to suppress the lytic cycle of bacteriophage 29 (52).…”

Section: Involvement Of the Phosphorelay In Sporulation Of Bsp1supporting

confidence: 76%

Sporulation during Growth in a Gut Isolate of Bacillus subtilis

et al. 2014

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Sporulation by Bacillus subtilis is a cell density-dependent response to nutrient deprivation. Central to the decision of entering sporulation is a phosphorelay, through which sensor kinases promote phosphorylation of Spo0A. The phosphorelay integrates both positive and negative signals, ensuring that sporulation, a time-and energy-consuming process that may bring an ecological cost, is only triggered should other adaptations fail. Here we report that a gastrointestinal isolate of B. subtilis sporulates with high efficiency during growth, bypassing the cell density, nutritional, and other signals that normally make sporulation a post-exponential-phase response. Sporulation during growth occurs because Spo0A is more active per cell and in a higher fraction of the population than in a laboratory strain. This in turn, is primarily caused by the absence from the gut strain of the genes rapE and rapK, coding for two aspartyl phosphatases that negatively modulate the flow of phosphoryl groups to Spo0A. We show, in line with recent results, that activation of Spo0A through the phosphorelay is the limiting step for sporulation initiation in the gut strain. Our results further suggest that the phosphorelay is tuned to favor sporulation during growth in gastrointestinal B. subtilis isolates, presumably as a form of survival and/or propagation in the gut environment.

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Section: Involvement Of the Phosphorelay In Sporulation Of Bsp1supporting

confidence: 76%

Sporulation during Growth in a Gut Isolate of Bacillus subtilis

et al. 2014

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“…Using single-cell analysis tools, we tested these predictions. In a previous study it was shown that there is a large cell-to-cell variability in low levels of spo0A expression during exponential growth (5). We now show that the other phosphorelay genes also show a large variability in gene expression ( Fig.…”

Section: Discussionsupporting

confidence: 53%

Heterochronic Phosphorelay Gene Expression as a Source of Heterogeneity in Bacillus subtilis Spore Formation

2010

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In response to limiting nutrient sources and cell density signals, Bacillus subtilis can differentiate and form highly resistant endospores. Initiation of spore development is governed by the master regulator Spo0A, which is activated by phosphorylation via a multicomponent phosphorelay. Interestingly, only part of a clonal population will enter this developmental pathway, a phenomenon known as sporulation bistability or sporulation heterogeneity. How sporulation heterogeneity is established is largely unknown. To investigate the origins of sporulation heterogeneity, we constructed promoter-green fluorescent protein (GFP) fusions to the main phosphorelay genes and perturbed their expression levels. Using time-lapse fluorescence microscopy and flow cytometry, we showed that expression of the phosphorelay genes is distributed in a unimodal manner. However, single-cell trajectories revealed that phosphorelay gene expression is highly dynamic or "heterochronic" between individual cells and that stochasticity of phosphorelay gene transcription might be an important regulatory mechanism for sporulation heterogeneity. Furthermore, we showed that artificial induction or depletion of the phosphorelay phosphate flow results in loss of sporulation heterogeneity. Our data suggest that sporulation heterogeneity originates from highly dynamic and variable gene activity of the phosphorelay components, resulting in large cell-to-cell variability with regard to phosphate input into the system. These transcriptional and posttranslational differences in phosphorelay activity appear to be sufficient to generate a heterogeneous sporulation signal without the need of the positive-feedback loop established by the sigma factor SigH.When nutrient sources are dwindling, the Gram-positive bacterium Bacillus subtilis can utilize a number of adaptive phenotypes such as the secretion of proteases and the development of genetic competence (for a recent review, see reference 49). The most sophisticated survival strategy that B. subtilis employs is the formation of a highly resistant endospore (34). Initiation of spore formation is governed by a complex multicomponent phosphorelay (Fig. 1) including the primary kinases KinA and KinB and two intermediate phosphotransferases, Spo0B and Spo0F (33). The phosphorelay activates Spo0A, the master sporulation regulator of sporulation, by phosphorylation (4), upon which phosphorylated Spo0A (Spo0AϳP) can directly regulate more than 100 genes (29). This induces a chain of events that takes several hours to complete and involves the activation of a set of alternative sigma factors that give unidirectionality to the cascade, culminating in the formation of the endospore (10).Interestingly, within isogenic populations of B. subtilis grown under identical conditions, not all cells enter this timely and costly developmental pathway. This type of phenotypic bifurcation is known as sporulation bistability or sporulation heterogeneity (9, 38). How populations of genetically identical cells bifurcate into phenoty...

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“…Unexpectedly, however, we found that the removal of O 1 -O 3 (⌬O 1-3 ) boosted Spo0A to high levels as early as T Ϫ0. 5 and bypassed the dependence of Spo0A accumulation on P v ; that is, in a mutant in which both P v and O 1 -O 3 had been removed (⌬P v ⌬O 1-3 ), Spo0A reached levels comparable to that seen for the wild type.…”

Section: Resultsmentioning

confidence: 99%

“…Meanwhile, the downstream promoter, P s , is silent due to the absence of both Spo0AϳP and H . Then, at the midexponential phase of growth, the gene (sigH) for H is derepressed (9) and Spo0AϳP begins to accumulate due to activation of kinases at the head of the phosphorelay other than KinA (5,9). Nonetheless, Spo0A synthesis continues to be maintained at a basal (although significant) level due to repression of P s via O 2 .…”

Section: Discussionmentioning

confidence: 99%

Just-in-Time Control of Spo0A Synthesis in Bacillus subtilis by Multiple Regulatory Mechanisms

Chastanet

Losick

2011

J Bacteriol

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The response regulator Spo0A governs multiple developmental processes in Bacillus subtilis, including most conspicuously sporulation. Spo0A is activated by phosphorylation via a multicomponent phosphorelay. Previous work has shown that the Spo0A protein is not rate limiting for sporulation. Rather, Spo0A is present at high levels in growing cells, rapidly rising to yet higher levels under sporulation-inducing conditions, suggesting that synthesis of the response regulator is subject to a just-in-time control mechanism. Transcription of spo0A is governed by a promoter switching mechanism, involving a vegetative, A -recognized promoter, P v , and a sporulation H -recognized promoter, P s , that is under phosphorylated Spo0A (Spo0AϳP) control. The spo0A regulatory region also contains four (including one identified in the present work) conserved elements that conform to the consensus binding site for Spo0AϳP binding sites. These are herein designated O 1 , O 2 , O 3 , and O 4 in reverse order of their proximity to the coding sequence. Here we report that O 1 is responsible for repressing P v during the transition to stationary phase, that O 2 is responsible for repressing P s during growth, that O 3 is responsible for activating P s at the start of sporulation, and that O 4 is dispensable for promoter switching. We also report that Spo0A synthesis is subject to a posttranscriptional control mechanism such that translation of mRNAs originating from P v is impeded due to RNA secondary structure whereas mRNAs originating from P s are fully competent for protein synthesis. We propose that the opposing actions of O 2 and O 3 and the enhanced translatability of mRNAs originating from P s create a highly sensitive, self-reinforcing switch that is responsible for producing a burst of Spo0A synthesis at the start of sporulation.

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kinC/D‐mediated heterogeneous expression of spo0A during logarithmical growth in Bacillus subtilis is responsible for partial suppression of φ29 development

Cited by 15 publications

References 57 publications

Sporulation during Growth in a Gut Isolate of Bacillus subtilis

Sporulation during Growth in a Gut Isolate of Bacillus subtilis

Heterochronic Phosphorelay Gene Expression as a Source of Heterogeneity in Bacillus subtilis Spore Formation

Just-in-Time Control of Spo0A Synthesis in Bacillus subtilis by Multiple Regulatory Mechanisms

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