A Single-Domain Response Regulator Functions as an Integrating Hub To Coordinate General Stress Response and Development in Alphaproteobacteria

Lori, Christian; Kaczmarczyk, Andreas; Jong, I. de; Jenal, Urs

doi:10.1128/mbio.00809-18

Cited by 36 publications

(53 citation statements)

References 69 publications

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“…For b-galactosidase assays strains harboring pAK502-based lacZ reporter plasmids were grown in 2 ml PYE supplemented with chloramphenicol and additional antibiotics as appropriate overnight at 30°C in a drum roller and diluted the next day 20-fold in 2 ml of the same medium, followed by further incubation for an additional 4.5 h under the same conditions before sampling. b-Galactosidase assays were performed as described before 36 . For b-galactosidase assays strains harboring pRKlac290-based plasmids were grown overnight in 5 ml PYE supplemented with the appropriate antibiotics in a roller drum at 30°C.…”

Section: β-Galactosidase Assaysmentioning

confidence: 99%

Precise transcription timing by a second-messenger drives a bacterial G1/S cell cycle transition

Kaczmarczyk

Hempel

Arx

et al. 2019

Preprint

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29Bacteria adapt their growth rate to their metabolic status and environmental 30 conditions by modulating the length of their quiescent G1 period. But the molecular 31 mechanisms controlling G1 length and exit from G1 are poorly understood. Here we 32 identify a key role for the second messenger c-di-GMP, and demonstrate that a gradual 33 increase in c-di-GMP concentration determines precise gene expression during G1/S in 34 Caulobacter crescentus. We show that c-di-GMP strongly stimulates the kinase ShkA, 35activates the TacA transcription factor, and initiates a G1/S-specific transcription 36 program leading to cell morphogenesis and S-phase entry. C-di-GMP activates ShkA by 37 binding to its central pseudo-receiver domain uncovering this wide-spread domain as a 38 novel signal input module of bacterial kinases. Activation of the ShkA-dependent 39 genetic program also causes c-di-GMP to reach peak levels, which triggers S-phase 40 entry and, in parallel, promotes proteolysis of ShkA and TacA. Thus, a gradual 41 increase of c-di-GMP results in a precisely tuned ShkA-TacA activity window enabling 42 G1/S specific gene expression before cells commit to replication initiation. By defining 43 a regulatory mechanism for G1/S control, this study contributes to understanding 44 bacterial growth control at the molecular level. cell division (D or G2) 1 . Since chromosome replication and cell division (C and D 49 periods) remain constant over a wide range of growth rates 2,3 , the step committing 50 cells to initiate chromosome replication largely determines bacterial proliferation rates. 51Bacteria like Escherichia coli or Bacillus subtilis can increase their growth rate by 52 bypassing the B period and by initiating replication multiple times per division cycle 2 . 53In contrast, Caulobacter crescentus strictly separates its cell cycle stages. An 54 asymmetric division generates a sessile stalked (ST) cell, which directly re-enters S-55 phase, and a motile swarmer (SW) cell that remains in G1 for a variable time 56 depending on nutrient availability 4,5 . Coincident with G1/S transition, motile SW cells 57 undergo morphogenesis to gain sessility ( Fig. 1a). But what determines the length of 58 G1 in this organism has remained unclear. 59In C. crescentus, replication initiation is regulated by the cell cycle kinase CckA. 60CckA is a bifunctional enzyme that acts as a kinase for the replication initiation 61 inhibitor CtrA in G1, but switches to being a phosphatase in S phase, resulting in the 62 inactivation of CtrA and clearance of the replication block 6 (Fig. 1a). The CckA switch 63 is governed by two response regulators, DivK and PleD. While DivK controls CckA 64 activity through protein-protein interactions 7-9 , PleD is a diguanylate cyclase, which is 65 responsible for the characteristic oscillation of c-di-GMP during the cell cycle 10 . The 66 concentration of c-di-GMP, below the detection limit in G1, increases during G1/S to 67 reach peak levels at the onset of S-phase 11 where it allosterically stimulates Cc...

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Section: β-Galactosidase Assaysmentioning

confidence: 99%

Precise transcription timing by a second-messenger drives a bacterial G1/S cell cycle transition

Kaczmarczyk

Hempel

Arx

et al. 2019

Preprint

Self Cite

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“…In addition, flagellar assembly indirectly affects hfiA transcription by an unknown mechanism [15]. Environmental signals such as nutrient quality and the two-component system (TCS) proteins LovK-LovR [14] and MrrA [16] influence hfiA transcription by unknown and independent mechanisms. CleA, a CheY-like response regulator that tunes flagellar rotation in response to cyclic-di-GMP binding, also regulates holdfast synthesis, though it is not known if CleA-mediated holdfast regulation involves HfiA [17].…”

Section: Introductionmentioning

confidence: 99%

“…There is good experimental support for the paradigm that TCS form insulated signaling systems, with little cross-regulation between noncognate kinases and responses regulators [19][20][21][22], though there are examples of branched TCS pathways in which sensor kinases signal to more than one regulator, or in which signals from multiple kinases converge on a single regulator (reviewed in [23,24]). Complex cellular processes including sporulation [25], stress responses [16,[26][27][28][29], biofilm formation [30], and cell cycle [31,32] are often controlled by multiple TCS in branched pathways. In this study, we have defined a regulatory system composed of multiple TCS proteins and transcription factors that regulates holdfast development in C. crescentus.…”

Section: Introductionmentioning

confidence: 99%

Regulation of bacterial surface attachment by a network of sensory transduction proteins

Ruiz

Fiebig²,

Crosson

2019

Preprint

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Bacteria are often attached to surfaces in natural ecosystems. A surface-associated lifestyle can have advantages, but shifts in the physiochemical state of the environment may result in conditions in which attachment has a negative fitness impact. Therefore, bacterial cells employ numerous mechanisms to control the transition from an unattached to a sessile state. The Caulobacter crescentus protein HfiA is a potent developmental inhibitor of the secreted polysaccharide adhesin known as the holdfast, which enables permanent attachment to surfaces. Multiple environmental cues influence expression of hfiA, but mechanisms of hfiA regulation remain largely undefined. Through a forward genetic selection, we have discovered a multi-gene network encoding a suite of twocomponent system (TCS) proteins and transcription factors that coordinately control hfiA transcription and surface adhesion. The hybrid HWE-family histidine kinase, SkaH, is central among these regulators and forms heteromeric complexes with the kinases, LovK and SpdS. The response regulator SpdR indirectly inhibits hfiA expression by activating two XRE-family transcription factors that directly bind the hfiA promoter to repress its transcription. This study provides evidence for a model in which a consortium of environmental sensors and transcriptional regulators integrate environmental cues at the hfiA promoter to control the attachment decision. Author summaryLiving on a surface within a community of cells confers a number of advantages to a bacterium. However, the transition from a free-living state to a surface-attached lifestyle should be tightly regulated to ensure that cells avoid adhering to toxic or resource-limited niches. Many bacteria build adhesive structures at their surfaces that enable attachment. We sought to discover genes that control development of the Caulobacter crescentus surface adhesin known as the holdfast. Our studies uncovered a network of signal transduction proteins that coordinately control the biosynthesis of the holdfast by regulating transcription of the holdfast inhibitor, hfiA. We conclude that C. crescentus uses a multi-component regulatory system to sense and integrate environmental information to determine whether to attach to a surface, or to remain in an unattached state.

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“…However, the major effect of deleting or overexpressing genes encoding LOV-HWE kinases appears to be dysregulation of the general stress response (GSR) system (Foreman et al, 2012, Kim et al, 2014, which determines cell survival across a range of stress conditions . There is increasing evidence that multiple HWE/HisKA2-family kinases function as part of complex regulatory networks that regulate the GSR in Alphaproteobacteria by influencing the phosphorylation state of the anti-anti-σ factor, PhyR (Kaczmarczyk et al, 2014, Gottschlich et al, 2018, Lori et al, 2018, Correa et al, 2013. Phospho-PhyR activates an extracytoplasmic function (ECF) σ factor -EcfG -by binding and sequestering its anti-σ factor, NepR (Figure 1).…”

Section: Lov-hwe Kinases: An Overviewmentioning

confidence: 99%

Regulation of theErythrobacter litoralisDSM 8509 general stress response by visible light

Fiebig

Varesio

Navarreto³

et al. 2019

Preprint

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Extracytoplasmic function (ECF) sigma factors are a major class of environmentallyresponsive transcriptional regulators. In Alphaproteobacteria the ECF sigma factor, σ EcfG , activates general stress response (GSR) transcription and protects cells from multiple stressors. A phosphorylation-dependent protein partner switching mechanism, involving HWE/HisKA_2-family histidine kinases, underlies σ EcfG activation. The identity of these sensor kinases and the signals that regulate them remain largely uncharacterized. We have developed the aerobic anoxygenic photoheterotrophic (AAP) bacterium, Erythrobacter litoralis DSM 8509, as a comparative genetic model to investigate GSR regulation. Using this system, we sought to define the contribution of visible light and a photosensory HWE kinase, LovK, to GSR transcription. We identified three HWE kinases that collectively regulate GSR: gsrK and lovK are activators, while gsrP is a repressor. GSR transcription is higher in the dark than light, and the opposing activities of gsrK and gsrP are sufficient to achieve light-dependent differential transcription. In the absence of gsrK and gsrP, lovK alone is sufficient to regulate GSR transcription in response to light. This regulation requires a photochemically active LOV domain in LovK. Our studies establish a role for visible light and HWE kinases in lightdependent regulation of GSR transcription in E. litoralis, an AAP species. GRAPHICAL ABSTRACT ABBREVIATED SUMMARYGeneral stress response (GSR) systems protect bacteria from a diverse range of physical and chemical stressors. We have developed Erythrobacter litoralis as a new genetic model to study GSR in Alphaproteobacteria and show that three HWE-family histidine kinases collectively regulate GSR transcription via σ EcfG . Visible light is a GSR regulatory signal in E. litoralis, and LovK is a blue-light photosensor kinase that functions as a dark activated GSR regulator.

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A Single-Domain Response Regulator Functions as an Integrating Hub To Coordinate General Stress Response and Development in Alphaproteobacteria

Cited by 36 publications

References 69 publications

Precise transcription timing by a second-messenger drives a bacterial G1/S cell cycle transition

Precise transcription timing by a second-messenger drives a bacterial G1/S cell cycle transition

Regulation of bacterial surface attachment by a network of sensory transduction proteins

Regulation of theErythrobacter litoralisDSM 8509 general stress response by visible light

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