A mutation that uncouples flagellum assembly from transcription alters the temporal pattern of flagellar gene expression in Caulobacter crescentus

Mangan, Erin; Bartamian, Miray; Gober, James W.

doi:10.1128/jb.177.11.3176-3184.1995

Cited by 37 publications

(103 citation statements)

References 64 publications

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“…2A) and that all Class III flagellar genes can be transcribed in Class II mutant strains that also contain a bfa mutation (Mangan et al, 1995). The fljL flagellin gene is subject to this same control.…”

Section: Regulation Of Class II Genesmentioning

confidence: 98%

Regulation of the Caulobacter flagellar gene hierarchy; not just for motility

Newton

1997

Molecular Microbiology

106

102

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SummaryThe Caulobacter crescentus flagellum serves not only as a motility apparatus, but also as a key landmark in the differentiation of this asymmetrically dividing bacterium. A distinctive aspect of flagellum biosynthesis is the periodic expression of the flagellar genes during the cell cycle in a sequence corresponding to the order of gene product assembly into the growing flagellum. This program of gene expression is achieved in part by the organization of flagellar genes into a four-tiered regulatory hierarchy that controls their expression at both the transcriptional and post-transcriptional levels. Because of the close interconnection of the developmental program to the asymmetric celldivision cycle in C. crescentus, studies of flagellar gene regulation and motility have also begun to reveal basic mechanisms responsible for control of the cell cycle itself. Here, we review recent work on regulation of the flagellar gene hierarchy in C. crescentus and consider regulatory mechanisms that are distinct from those described in Escherichia coli and Salmonella typhimurium.

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Section: Regulation Of Class II Genesmentioning

confidence: 98%

Regulation of the Caulobacter flagellar gene hierarchy; not just for motility

Newton

1997

Molecular Microbiology

106

102

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“…In Caulobacter, the molecular basis for the coupling of assembly of the £agellum with gene expression is not clear yet. Mutations that bypass the requirement of the ¢rst £agellar checkpoint (products of class II genes) for the transcription of class III genes and the £jL £agellin gene have been isolated and termed bfa (bypass of £agellar assembly) [38]. Both £jL and £jK are transcribed in bfa mutants but the corresponding £ag-ellin proteins are not synthesized, suggesting that both genes are also subject to post-transcriptional control [38].…”

Section: Polar Morphogenesismentioning

confidence: 99%

“…Mutations that bypass the requirement of the ¢rst £agellar checkpoint (products of class II genes) for the transcription of class III genes and the £jL £agellin gene have been isolated and termed bfa (bypass of £agellar assembly) [38]. Both £jL and £jK are transcribed in bfa mutants but the corresponding £ag-ellin proteins are not synthesized, suggesting that both genes are also subject to post-transcriptional control [38]. Both genes are also transcribed in all class III £agellar mutants tested but their mRNA is not translated in the absence of any of the known class III proteins [39].…”

Section: Polar Morphogenesismentioning

confidence: 99%

Signal transduction mechanisms in Caulobacter crescentus development and cell cycle control

Jenal

2000

FEMS Microbiology Reviews

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The life cycle of the aquatic bacterium Caulobacter crescentus includes an asymmetric cell division and an obligate cell differentiation. Each cell division gives rise to a motile but replication inert swarmer cell and a sessile, replication competent stalked cell. While the stalked progeny immediately reinitiates DNA replication and cell division, the swarmer cell remains motile and chemotactically active for a constant period of the cell cycle before it differentiates into a stalked cell. During this process, the cell looses motility by ejecting the flagellum, synthesizes a stalk and eventually initiates chromosome replication and cell division. The link of morphogenic transitions to the replicative cycle of Caulobacter implies that the developmental programs which determine asymmetry and cell differentiation must be tightly connected with cell cycle control. This has been confirmed by the recent identification of signal transduction mechanisms, which are involved in temporal and spatial control of both development and cell cycle. Interestingly, the cell has recruited two-component signal transduction systems for this internal control, a family of regulatory proteins which usually are involved in the information transfer between the environment and the inside of a cell. The response regulator protein CtrA controls several key cell cycle events like the initiation of DNA replication, DNA methylation, cell division, and flagellar biogenesis. The activity of this master regulator is subject to complex temporal and spatial control during the C. crescentus cell cycle, including regulated transcription, phosphorylation and degradation. Three membrane bound sensor kinases have been proposed to control the phosphorylation status of CtrA. Two of these, CckA and DivJ, exhibit specific subcellular localization and, in the case of CckA, dynamic rearrangement in the course of the cell cycle. These findings support the idea that the developmental program of C. crescentus is controlled at least in part by localized cues that act as checkpoints for the control of morphological changes and cell cycle progression. ß

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“…Flagellum synthesis requires nearly 50 genes, most of which are transcribed at a defined time in the cell cycle. Additionally, flagellar gene expression is influenced by a trans-acting regulatory hierarchy in which the expression and successful assembly of gene products that comprise early flagellar substructures are required for the expression of gene products incorporated later into the nascent flagellum (Newton et al, 1989;Xu et al, 1989;Ramakrishnan et al, 1994;Mangan et al, 1995). Epistasis experiments have demonstrated that this regulatory cascade consists of four hierarchical classes (Fig.…”

Section: Introductionmentioning

confidence: 99%

“…The cascade initiates with the temporal activation of the global transcription factor CtrA (class I), which, in turn, activates the transcription of the class II genes encoding the MS ring of the basal body, the flagellar switch and the flagellum-specific type III secretion system (TTSS) (Quon et al, 1996;Domian et al, 1997;Reisenauer et al, 1999). The assembly of this class IIencoded structure is required for the transcription of the flagellar class III and IV genes, encoding the basal bodyhook complex and the flagellin-containing filament, respectively (Newton et al, 1989;Xu et al, 1989;Ramakrishnan et al, 1994;Mangan et al, 1995). Thus, an assembly checkpoint functions to inhibit class III/IV gene expression until the class II-encoded structure is completed (Mangan et al, 1995;Muir & Gober, 2002).…”

Section: Introductionmentioning

confidence: 99%

The trans-acting flagellar regulatory proteins, FliX and FlbD, play a central role in linking flagellar biogenesis and cytokinesis in Caulobacter crescentus

2005

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The FliX/FlbD-dependent temporal transcription of late flagellar genes in Caulobacter crescentus requires the assembly of an early, class II-encoded flagellar structure. Class II flagellar-mutant strains exhibit a delay in the completion of cell division, with the accumulation of filamentous cells in culture. It is shown here that this cell-division defect is attributable to an arrest in the final stages of cell separation. Normal cell morphology could be restored in class II mutants by gain-of-function alleles of FliX or FlbD, suggesting that the timely completion of cell division requires these trans-acting factors. In synchronized cultures, inhibition of cell division by depleting FtsZ resulted in normal initial expression of the late, FlbD-dependent fliK gene; however, the cell cycle-regulated cessation of transcription was delayed, indicating that cell division may be required to negatively regulate FlbD activity. Interestingly, prolonged depletion of FtsZ resulted in an eventual loss of FlbD activity that could be bypassed by a constitutive mutant of FlbD, but not of FliX, suggesting the possible existence of a second cell cycle-dependent pathway for FlbD activation.

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A mutation that uncouples flagellum assembly from transcription alters the temporal pattern of flagellar gene expression in Caulobacter crescentus

Cited by 37 publications

References 64 publications

Regulation of the Caulobacter flagellar gene hierarchy; not just for motility

Regulation of the Caulobacter flagellar gene hierarchy; not just for motility

Signal transduction mechanisms in Caulobacter crescentus development and cell cycle control

The trans-acting flagellar regulatory proteins, FliX and FlbD, play a central role in linking flagellar biogenesis and cytokinesis in Caulobacter crescentus

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