Proteolysis of beta-galactosidase following SigmaB activation in Bacillus subtilis
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BiBTeXIn Bacillus subtilis the σB mediated general stress response provides protection against various environmental and energy related stress conditions. To better understand the general stress response, we need to explore the mechanism by which the components interact. Here, we performed experiments in B. subtilis wild type and mutant strains to test and validate a mathematical model of the dynamics of σB activity. In the mutant strain BSA115, σB transcription is inducible by the addition of IPTG and negative control of σB activity by the anti-sigma factor RsbW is absent. In contrast to our expectations of a continuous β-galactosidase activity from a ctc::lacZ fusion, we observed a transient activity in the mutant. To explain this experimental finding, we constructed mathematical models reflecting different hypotheses regarding the regulation of σB and β-galactosidase dynamics. Only the model assuming instability of either ctc::lacZ mRNA or β-galactosidase protein is able to reproduce the experiments in silico. Subsequent Northern blot experiments revealed stable high-level ctc::lacZ mRNA concentrations after the induction of the σB response. Therefore, we conclude that protein instability following σB activation is the most likely explanation for the experimental observations. Our results thus support the idea that B. subtilis increases the cytoplasmic proteolytic degradation to adapt the proteome in face of environmental challenges following activation of the general stress response. The findings also have practical implications for the analysis of stress response dynamics using lacZ reporter gene fusions, a frequently used strategy for the σB response.
SEEK ID: https://fairdomhub.org/publications/149
DOI: 10.1039/C2MB25031D
Projects: BaCell-SysMO
Publication type: Not specified
Journal: Mol. BioSyst.
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Date Published: 2012
Registered Mode: Not specified
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Created: 2nd May 2012 at 11:34
Last updated: 8th Dec 2022 at 17:26
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Biological problem addressed: Gene Expression
Investigation: The transition from growing to non-growing Baci...
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Creator: Ulf Liebal
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The figure contains information necessary to understand the mathematical model of experiments in BSA115. In these experiments sigB response is artificially initiated by the addition of IPTG while sigB is downstream of a Pspac promoter. The figure shows a flow-chart diagram that combines three hypotheses to explain experiments. It contains the ODEs and the fit of the respective models to the data.
Creator: Ulf Liebal
Submitter: Ulf Liebal
only lacZ synthesis reduced by inhibitor in BSA115
Creator: Ulf Liebal
Submitter: Ulf Liebal
Model type: Ordinary differential equations (ODE)
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Model type: Ordinary differential equations (ODE)
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Model type: Ordinary differential equations (ODE)
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Environment: JWS Online
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