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Updated: Sep 26, 2026

A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues
Published on: February 19, 2019
Styrene-catabolism regulation in Pseudomonas fluorescens ST: phosphorylation of StyR induces dimerization and
Livia Leoni1, Paolo Ascenzi, Alessio Bocedi
1Dipartimento di Biologia, Università Roma Tre, Viale G. Marconi 446, I-00146 Rome, Italy.
Abstract:
Styrene is an important chemical extensively used in the petrochemical and polymer industries. In Pseudomonas fluorescens ST, styrene metabolism is controlled by a two-component regulatory system, very uncommon in the degradation of aromatic compounds. The two-component regulatory proteins StyS and StyR regulate the expression of the styABCD operon, which codes for styrene degradation. StyS corresponds to the sensor kinase and StyR to the response regulator, which is essential for the activation of PstyA, the promoter of the catabolic operon. In two-component systems, the response regulator is phosphorylated by the cognate sensor kinase. Phosphorylation activates the response regulator, inducing DNA-binding. The mechanism underlying this activation has been reported only for a very few response regulators. Here, the effect of phosphorylation on the oligomeric state and on the DNA-binding properties of StyR has been investigated. Phosphorylation induces dimerization of StyR, the affinity of dimeric StyR for the target DNA is higher than that of the monomer, moreover dimeric StyR binding to the DNA target is cooperative. Furthermore, StyR oligomerization may be driven by the DNA target. This is the first direct demonstration that StyR response regulator binds to the PstyA promoter.
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