Identification of genes regulated by the MvaT-like paralogues TurA and TurB of Pseudomonas putida KT2440.

The genome of the Pseudomonas putida strain KT2440 contains five paralogous proteins (TurA, TurB, TurC, TurD and TurE) of the H-NS-like MvaT class of transcription regulators. TurA and TurB belong to groups I and II, respectively, both containing orthologous MvaT proteins that are present in all Pseudomonadaceae species. On the contrary, TurC, TurD and TurE belong to group III, which contains species-specific paralogous MvaT proteins.

Transcriptional wiring of the TOL plasmid regulatory network to its host involves the submission of the sigma54-promoter Pu to the response regulator PprA.

Implantation of the regulatory circuit of the degradation pathway of TOL plasmid pWW0 in the native transcriptional network of the host Pseudomonas putida involves interplay between plasmid- and chromosome-encoded factors. We have employed a reverse genetics approach to investigate such a molecular wiring by identifying host proteins that form stable complexes with Pu, the sigma(54)-dependent promoter of the upper TOL operon of pWW0. This approach revealed that the Pu upstream activating sequences (UAS), the target sites of the cognate activator XylR, form a specific complex with a host protein which, following DNA affinity purification and mass spectrometry analysis, was identified as the LytTR-type two-component response regulator PprA.

Novel auto-inducing expression systems for the development of whole-cell biocatalysts.

Novel expression systems for the development of whole-cell biocatalysts were generated. Their novelty consists both in the host, Pseudomonas putida, and in the ability to auto-induce the expression of genes of interest at the exhaustion of the carbon source used for the biomass growth. The auto-induction relies on new expression vectors developed in this study and based on the activator TouR from Pseudomonas sp.

Styrene lower catabolic pathway in Pseudomonas fluorescens ST: identification and characterization of genes for phenylacetic acid degradation.

Pseudomonas fluorescens ST is a styrene degrading microorganism that, by the sequential oxidation of the vinyl side chain, converts styrene to phenylacetic acid. The cluster of styrene upper pathway catabolic genes (sty genes) has been previously localized on a chromosomal region. This report describes the isolation, sequencing and analysis of a new chromosomal fragment deriving from the ST strain genomic bank that contains the styrene lower degradative pathway genes (paa genes), involved in the metabolism of phenylacetic acid.

TouR-mediated effector-independent growth phase-dependent activation of the sigma54 Ptou promoter of Pseudomonas stutzeri OX1.

Transcription of the catabolic touABCDEF operon, encoding the toluene-o-xylene monooxygenase of Pseudomonas stutzeri OX1, is driven by the sigma(54)-dependent Ptou promoter, whose activity is controlled by the phenol-responsive NtrC-like activator TouR. In this paper we describe for the first time a peculiar characteristic of this system, namely, that Ptou transcription is activated in a growth phase-dependent manner in the absence of genuine effectors of the cognate TouR regulator. This phenomenon, which we named gratuitous activation, was observed in the native strain P.