Precise timing of transcription by c-di-GMP coordinates cell cycle and morphogenesis in Caulobacter

Kaczmarczyk, Andreas; Hempel, Antje M.; Arx, C. von; Böhm, Raphael; Dubey, Badri N.; Nesper, Jutta; Schirmer, Tilman; Hiller, Sebastian; Jenal, Urs

doi:10.1038/s41467-020-14585-6

Cited by 44 publications

(63 citation statements)

References 44 publications

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“…crescentus (48,75), and our results suggest that the status of flagellar assembly feeds into this developmental program by regulating PleD phosphorylation (Fig 4A). Whether the flagellum controls PleD phosphorylation through the DivJ-PleC kinase-phosphatase pair (52) or through a separate phosphorelay will require additional dissection of how fss genes link flagellar assembly to cell cycle progression.…”

Section: Discussionsupporting

confidence: 52%

Flagellar perturbations activate adhesion through two distinct pathways inCaulobacter crescentus

Hershey

Fiebig

Crosson

2020

Preprint

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Bacteria carry out sophisticated developmental programs to colonize exogenous surfaces. The rotary flagellum, a dynamic machine that drives motility, is a key regulator of surface colonization. The specific signals recognized by flagella and the pathways by which those signals are transduced to coordinate adhesion remain subjects of debate. Mutations that disrupt flagellar assembly in the dimorphic bacterium Caulobacter crescentus stimulate the production of a polysaccharide adhesin called the holdfast. Using a genome-wide phenotyping approach, we compared surface adhesion profiles in wild-type and flagellar mutant backgrounds of C. crescentus. We identified a diverse set of flagellar mutations that enhance adhesion by inducing a hyper-holdfast phenotype and discovered a second set of mutations that suppress this phenotype. Epistasis analysis of the flagellar signaling suppressor (fss) mutations demonstrated that the flagellum stimulates holdfast production via two genetically distinct pathways. The developmental regulator PleD contributes to holdfast induction in mutants disrupted at both early and late stages of flagellar assembly. Mutants disrupted at late stages of flagellar assembly, which retain an intact rotor complex, induce holdfast production through an additional process that requires the MotAB stator and its associated diguanylate cyclase, DgcB. We have assigned a subset of the fss genes to either the stator- or pleD-dependent networks and characterized two previously unidentified motility genes that contribute to the stator-dependent pathway. We propose a model in which the flagellum integrates both developmental and mechanical stimuli to coordinate adhesion.ImportanceUnderstanding how bacteria colonize solid surfaces is of significant clinical, industrial and ecological importance. In this study, we identified genes that are required for Caulobacter crescentus to activate surface attachment in response to signals from a macromolecular machine called the flagellum. Genes involved in transmitting information from the flagellum can be grouped into separate pathways, those that control the C. crescentus developmental program and those that are required for flagellar rotation. Our results support a model in which a developmental and a mechanical signaling pathway operate in parallel downstream of the flagellum and converge to regulate adhesion. We conclude that the flagellum serves as a signaling hub by integrating internal and external cues to coordinate surface colonization and emphasize the role of signal integration in linking complex sets of environmental stimuli to individual behaviors.

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Section: Discussionsupporting

confidence: 52%

Flagellar perturbations activate adhesion through two distinct pathways inCaulobacter crescentus

Hershey

Fiebig

Crosson

2020

Preprint

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“…Each pathway includes a diguanylate cyclase predicted to synthesize bis-(39-59)-cyclic diguanosine monophosphate (c-di-GMP), a second messenger that promotes surface-associated behaviors in bacteria (52). In C. crescentus, c-di-GMP binds numerous downstream effectors to activate stalk assembly (53), cell cycle progression (54,55), and holdfast synthesis (40,56). To test the role of cdi-GMP synthesis in linking cues from the flagellum to holdfast production, we examined catalytically inactive alleles of pleD and dgcB.…”

Section: Resultsmentioning

confidence: 99%

Flagellar Perturbations Activate Adhesion through Two Distinct Pathways in Caulobacter crescentus

Hershey

Fiebig

Crosson

2021

mBio

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Bacteria carry out sophisticated developmental programs to colonize exogenous surfaces. The rotary flagellum, a dynamic machine that drives motility, is a key regulator of surface colonization. The specific signals recognized by flagella and the pathways by which those signals are transduced to coordinate adhesion remain subjects of debate. Mutations that disrupt flagellar assembly in the dimorphic bacterium Caulobacter crescentus stimulate the production of a polysaccharide adhesin called the holdfast. Using a genomewide phenotyping approach, we compared surface adhesion profiles in wild-type and flagellar mutant backgrounds of C. crescentus. We identified a diverse set of flagellar mutations that enhance adhesion by inducing a hyperholdfast phenotype and discovered a second set of mutations that suppress this phenotype. Epistasis analysis of the flagellar signaling suppressor (fss) mutations demonstrated that the flagellum stimulates holdfast production via two genetically distinct pathways. The developmental regulator PleD contributes to holdfast induction in mutants disrupted at both early and late stages of flagellar assembly. Mutants disrupted at late stages of flagellar assembly, which assemble an intact rotor complex, induce holdfast production through an additional process that requires the MotAB stator and its associated diguanylate cyclase, DgcB. We have assigned a subset of the fss genes to either the stator- or pleD-dependent networks and characterized two previously unidentified motility genes that regulate holdfast production via the stator complex. We propose a model through which the flagellum integrates mechanical stimuli into the C. crescentus developmental program to coordinate adhesion. IMPORTANCE Understanding how bacteria colonize solid surfaces is of significant clinical, industrial and ecological importance. In this study, we identified genes that are required for Caulobacter crescentus to activate surface attachment in response to signals from a macromolecular machine called the flagellum. Genes involved in transmitting information from the flagellum can be grouped into separate pathways, those that control the C. crescentus morphogenic program and those that are required for flagellar motility. Our results support a model in which a developmental and a mechanical signaling pathway operate in parallel downstream of the flagellum and converge to regulate adhesion. We conclude that the flagellum serves as a signaling hub by integrating internal and external cues to coordinate surface colonization and emphasize the role of signal integration in linking complex sets of environmental stimuli to individual behaviors.

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“…From an engineering perspective, coupling surface sensing via the inner membrane PilA reservoir to a c-di-GMP secondmessenger cascade provides a mechanism to couple cell-cycle initiation to multiple orthogonal output functions, including inhibition of flagellar motility (51), secretion of adhesive surface polysaccharides (9), and activation of stalk cell-specific transcriptional programs (28) to induce permanent surface attachment and cellular differentiation at the G 1 -S phase transition.…”

Section: Discussionmentioning

confidence: 99%

“…Among them, we found the sensor kinase PleC that functions upstream and activates the diguanylate cyclase PleD over phosphorylation. The hybrid kinase ShkA comprises a downstream effector protein of PleD, which binds c-di-GMP and phosphorylates the TacA transcription factor responsible for the initiation of the stalked cellspecific transcription program (27,28). The flagellum assembly ATPase FlbE/FliH together with FliI and FliJ form the soluble component of the flagellar export apparatus, which, in Pseudomonas, has also been identified as a c-di-GMP effector complex (29).…”

Section: Components Of the C-di-gmp Signaling Network Are Conditionallymentioning

confidence: 99%

The type IV pilin PilA couples surface attachment and cell-cycle initiation in Caulobacter crescentus

Medico

Cerletti

Schächle

et al. 2020

Proc. Natl. Acad. Sci. U.S.A.

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Understanding how bacteria colonize surfaces and regulate cell-cycle progression in response to cellular adhesion is of fundamental importance. Here, we use transposon sequencing in conjunction with fluorescence resonance energy transfer (FRET) microscopy to uncover the molecular mechanism for how surface sensing drives cell-cycle initiation in Caulobacter crescentus. We identify the type IV pilin protein PilA as the primary signaling input that couples surface contact to cell-cycle initiation via the second messenger cyclic di-GMP (c-di-GMP). Upon retraction of pili filaments, the monomeric pilin reservoir in the inner membrane is sensed by the 17-amino acid transmembrane helix of PilA to activate the PleC-PleD two-component signaling system, increase cellular c-di-GMP levels, and signal the onset of the cell cycle. We termed the PilA signaling sequence CIP for “cell-cycle initiating pilin” peptide. Addition of the chemically synthesized CIP peptide initiates cell-cycle progression and simultaneously inhibits surface attachment. The broad conservation of the type IV pili and their importance in pathogens for host colonization suggests that CIP peptide mimetics offer strategies to inhibit surface sensing, prevent biofilm formation and control persistent infections.

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Precise timing of transcription by c-di-GMP coordinates cell cycle and morphogenesis in Caulobacter

Cited by 44 publications

References 44 publications

Flagellar perturbations activate adhesion through two distinct pathways inCaulobacter crescentus

Flagellar perturbations activate adhesion through two distinct pathways inCaulobacter crescentus

Flagellar Perturbations Activate Adhesion through Two Distinct Pathways in Caulobacter crescentus

The type IV pilin PilA couples surface attachment and cell-cycle initiation in Caulobacter crescentus

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