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Temporal controls of the asymmetric cell division cycle in Caulobacter crescentus.

Li S, Brazhnik P, Sobral B, Tyson JJ - PLoS Comput. Biol. (2009)

Bottom Line: The asymmetric cell division cycle of Caulobacter crescentus is orchestrated by an elaborate gene-protein regulatory network, centered on three major control proteins, DnaA, GcrA and CtrA.The model is validated against observed phenotypes of wild-type cells and relevant mutants, and it predicts the phenotypes of novel mutants and of known mutants under novel experimental conditions.Because the cell cycle control proteins of Caulobacter are conserved across many species of alpha-proteobacteria, the model we are proposing here may be applicable to other genera of importance to agriculture and medicine (e.g., Rhizobium, Brucella).

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.

ABSTRACT
The asymmetric cell division cycle of Caulobacter crescentus is orchestrated by an elaborate gene-protein regulatory network, centered on three major control proteins, DnaA, GcrA and CtrA. The regulatory network is cast into a quantitative computational model to investigate in a systematic fashion how these three proteins control the relevant genetic, biochemical and physiological properties of proliferating bacteria. Different controls for both swarmer and stalked cell cycles are represented in the mathematical scheme. The model is validated against observed phenotypes of wild-type cells and relevant mutants, and it predicts the phenotypes of novel mutants and of known mutants under novel experimental conditions. Because the cell cycle control proteins of Caulobacter are conserved across many species of alpha-proteobacteria, the model we are proposing here may be applicable to other genera of importance to agriculture and medicine (e.g., Rhizobium, Brucella).

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Simulation of ctrA constitutive expression.ctrA is constitutively expressed at 30% of its wild-type promoter activity: ks,ctrA-P1 = ks,ctrA-P2 = 0, k ′ = 0.048.
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pcbi-1000463-g008: Simulation of ctrA constitutive expression.ctrA is constitutively expressed at 30% of its wild-type promoter activity: ks,ctrA-P1 = ks,ctrA-P2 = 0, k ′ = 0.048.

Mentions: When ctrA is constitutively expressed (the only copy of ctrA gene is on pJS14), the cell cycle is normal [37]. In our simulation (Figure 8), constitutive ctrA expression at mild level (20%∼80% of wild-type ctrA promoter activity) does not affect the normal cell cycle. Insignificant deviations, similar to those for the ctrAD51E mutant, were observed for some proteins, Z-ring closing time, and DNA methylation. If ctrA is expressed constitutively at <20% of the wild-type level, then CtrA∼P never increases high enough to prompt expression of other essential genes, and the cell cannot proceed through the division cycle normally. The simulation results for this case are similar to those of ΔctrA mutant (data not shown here; see figure at the website http://mpf.biol.vt.edu/research/caulobacter/SWST/pp/).


Temporal controls of the asymmetric cell division cycle in Caulobacter crescentus.

Li S, Brazhnik P, Sobral B, Tyson JJ - PLoS Comput. Biol. (2009)

Simulation of ctrA constitutive expression.ctrA is constitutively expressed at 30% of its wild-type promoter activity: ks,ctrA-P1 = ks,ctrA-P2 = 0, k ′ = 0.048.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2714070&req=5

pcbi-1000463-g008: Simulation of ctrA constitutive expression.ctrA is constitutively expressed at 30% of its wild-type promoter activity: ks,ctrA-P1 = ks,ctrA-P2 = 0, k ′ = 0.048.
Mentions: When ctrA is constitutively expressed (the only copy of ctrA gene is on pJS14), the cell cycle is normal [37]. In our simulation (Figure 8), constitutive ctrA expression at mild level (20%∼80% of wild-type ctrA promoter activity) does not affect the normal cell cycle. Insignificant deviations, similar to those for the ctrAD51E mutant, were observed for some proteins, Z-ring closing time, and DNA methylation. If ctrA is expressed constitutively at <20% of the wild-type level, then CtrA∼P never increases high enough to prompt expression of other essential genes, and the cell cannot proceed through the division cycle normally. The simulation results for this case are similar to those of ΔctrA mutant (data not shown here; see figure at the website http://mpf.biol.vt.edu/research/caulobacter/SWST/pp/).

Bottom Line: The asymmetric cell division cycle of Caulobacter crescentus is orchestrated by an elaborate gene-protein regulatory network, centered on three major control proteins, DnaA, GcrA and CtrA.The model is validated against observed phenotypes of wild-type cells and relevant mutants, and it predicts the phenotypes of novel mutants and of known mutants under novel experimental conditions.Because the cell cycle control proteins of Caulobacter are conserved across many species of alpha-proteobacteria, the model we are proposing here may be applicable to other genera of importance to agriculture and medicine (e.g., Rhizobium, Brucella).

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.

ABSTRACT
The asymmetric cell division cycle of Caulobacter crescentus is orchestrated by an elaborate gene-protein regulatory network, centered on three major control proteins, DnaA, GcrA and CtrA. The regulatory network is cast into a quantitative computational model to investigate in a systematic fashion how these three proteins control the relevant genetic, biochemical and physiological properties of proliferating bacteria. Different controls for both swarmer and stalked cell cycles are represented in the mathematical scheme. The model is validated against observed phenotypes of wild-type cells and relevant mutants, and it predicts the phenotypes of novel mutants and of known mutants under novel experimental conditions. Because the cell cycle control proteins of Caulobacter are conserved across many species of alpha-proteobacteria, the model we are proposing here may be applicable to other genera of importance to agriculture and medicine (e.g., Rhizobium, Brucella).

Show MeSH