Article

Role of BvgA phosphorylation and DNA binding affinity in control of Bvg-mediated phenotypic phase transition in Bordetella pertussis

Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, CA 93109-9610, USA.
Molecular Microbiology (Impact Factor: 4.42). 12/2005; 58(3):700-13. DOI: 10.1111/j.1365-2958.2005.04875.x
Source: PubMed

ABSTRACT

To investigate the mechanism by which the Bordetella BvgAS phosphorelay controls expression of at least three distinct phenotypic phases, we isolated and characterized two B. pertussis mutants that were able to express Bvg- and Bvg(i) phase phenotypes but not Bvg+ phase phenotypes. In both cases, the mutant phenotype was due to a single nucleotide change in bvgA resulting in a single amino acid substitution in BvgA. In vitro phosphorylation assays showed that BvgA containing the T194M substitution was significantly impaired in its ability to use either BvgS or acetyl phosphate as a substrate for phosphorylation. Binding studies indicated that this mutant protein was able to bind an oligonucleotide containing a high-affinity BvgA binding site in a manner similar to wild-type BvgA, but was defective for binding the fhaB promoter in the absence of RNA polymerase (RNAP). By contrast, BvgA containing the R152H substitution had wild-type phosphorylation properties but was severely defective in its ability to bind either the high-affinity BvgA binding site-containing oligonucleotide or the fhaB promoter by itself. Both mutant BvgA proteins were able to bind the fhaB promoter in the presence of RNAP however, demonstrating the profound effect that RNAP has on stabilizing the ternary complexes between promoter DNA, BvgA and RNAP. Our results are consistent with the hypothesis that BvgAS controls expression of multiple phenotypic phases by adjusting the intracellular concentration of BvgA-P and they demonstrate the additive nature of BvgA binding site affinity and protein-protein interactions at different Bvg-regulated promoters.

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Available from: Allison M Jones, Dec 16, 2014
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    • "The solid, dashed and dotted lines are for WT, R152H and T194M, respectively. The symbols are experimental results due to Jones el al.[24]. In the figure legend Th and Expt stand for theoretical and experimental data, respectively.The cost function and the optimization profiles of the kinetic parameters associated with the simulation of in vitro phosphorylation assay results (Fig 4 and Table 3) as a function of SA steps. "
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    ABSTRACT: To understand the switching of different phenotypic phases of Bordetella pertussis, we propose an optimized mathematical framework for signal transduction through BvgAS two-component system. The response of the network output to the sensory input has been demonstrated in steady state. An analysis in terms of local sensitivity amplification characterizes the nature of the molecular switch. The sensitivity analysis of the model parameters within the framework of various correlation coefficients helps to decipher the contribution of the modular structure in signal propagation. Once classified, the model parameters are tuned to generate the behavior of some novel strains using simulated annealing, a stochastic optimization technique.
    Full-text · Article · Jan 2016 · PLoS ONE
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    • "The expression of B. pertussis virulence factors is controlled by the two-component BvgAS sensory transduction system [1], [15], [16]. BvgAS controls the expression of a spectrum of phenotypic phases transitioning between a virulent (Bvg+) phase and a nonvirulent (Bvg-) phase, which is referred to as phenotypic modulation [17]–[20]. During the virulent Bvg+ phase, the BvgAS system controls the expression of over 100 virulence genes [21] by binding phosphorylated BvgA to the promoters of the virulence genes. "
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    • "This finding suggests a possible two-component signal transduction system, where the periplasmic sensor histidine kinase is responsible for sensing stimuli and a second component regulates the virulence effector, namely the TAA gene (Figure 5). The bacterial prototype for this system is the Bordetella pertussis BvgAS two-component regulatory system which is involved in the expression of many adhesins and toxins (Jones et al., 2005). It is now important to obtain experimental data in order to validate the hypothesis raised by this in silico analysis. "
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