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 physiological modulation of the Pu promoter of TOL plasmid: negative regulatory role of the TurA protein of Pseudomonas putida in the response to suboptimal growth temperatures.

From crude protein extracts of Pseudomonas putida KT2440, we identified a small protein, TurA, able to bind to DNA fragments bearing the entire Pu promoter sequence of the TOL plasmid. The knock-out inactivation of the turA gene resulted in enhanced transcription initiation from the Pu promoter, initially suggesting a negative regulatory role of TurA on Pu expression. Ectopic expression of TurA both in P.