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Research groups

Cell biology and Biotechnology

Dr Inés Canosa. UPO
Global regulation of nitrogen and carbon metabolism in Pseudomonas putida KT2440
Dr Inés Canosa. UPO
Researcher associated to Dr Eduardo Santero Santurino. UPO

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Summary

Our group is interested in the characterization of the overall response of Pseudomonas putida in its adaptation to the availability of nutrients in the environment. The genus Pseudomonas within the g-Proteobacteria constitutes a large, diverse group of ubiquitous bacteria that inhabit soil, water, plants and animals, and are well known for their broad metabolic versatility and genetic plasticity. They are nutritionally versatile, in general grow quickly and are particularly renowed for their ability to metabolize toxic organic compounds, such as aliphatic and aromatic hydrocarbons. The ubiquity of P. putida reflects a highly developed ability to adapt to the different and varying physico-chemical conditions it faces in unpolluted or polluted environments. This ability involves the monitoring of a variety of environmental signals, the integration of this information within the information on the physiological status of the cell and the appropriate tuning of the complex regulatory network that controls cellular metabolism. P. putida is able to integrate two different signals; the presence of an existing compound triggers a controlled specific mechanism of assimilation of such compound as carbon and/or nitrogen source. Besides such specific control mechanism, there is frequently an overimposed global control that responds to the relative abundance of other compounds that can be also used as carbon or nitrogen source.

We are particularly focused in the global control of gene regulation in the assimilation of different compounds as sole carbon and nitrogen sources. Nitrogen is one of the most limiting elements in the environment. Bacteria have learnt to find their way in order to scavenge alternative nitrogen sources when the preferential sources are scarce. We have previously defined NtrC as the master nitrogen regulator in P. putida, and we are interested in the elucidation of the mechanisms this regulatory system exerts in the control of nitrogen assimilation. 

In recent times, we have focused our efforts on the characterization of the two component system CbrAB in the uptake of carbon in P. putida. This system is unique in the genus Pseudomonas, and therefore could participate in the great adaptive capacity of bacteria of this genus. While the signal of the Cbr system remains unknown, this system was suggested to function co-ordinately with Ntr to maintain the carbon-nitrogen balance. We have performed a transcriptomic approach on CbrB regulation, and are working in the definition of a consensus sequence in the DNA targets. We are also trying to elucidate the role of the histidine kinase CbrA in the signal sensing that activates the regulatory system.