Regulation of nutrient uptake in Pseudomoas aeruginosa PAO1.

P. aeruginosa, a versatile ubiquitous Gram-negative bacterium and opportunistic pathogen, has a phenomenal capacity to adapt to different environments and degrades a wide variety of different organic molecules as carbon and energy sources. This is not surprising as its genome contains an unusually large number of genes for catabolism, nutrient transport and metabolic regulation. P. aeruginosa chooses specific substrates in the environment and uses them as carbon and energy sources. The preferred carbon and energy source of P. aeruginosa PAO1 is succinate, which enters the cell via redundant uptake systems. The expression of the dctA gene coding for a succinate transport protein has been shown to be regulated positively by Hfq. From previous work, we could confirm that dctA transcription depends on Hfq, suggesting that Hfq and an unknown sRNA regulate either a repressor(s) and/or an activator(s) of dctA transcription.

The aim of Ms Valentini’s thesis is to study the regulation of the dct system in P. aeruginosa PAO1, in particular the regulation of the dctA transporter gene by the Hfq protein. We postulate that a novel sRNA accounts for this regulation. In her studies, she will extend our knowledge of the global regulatory roles of Hfq and sRNAs with respect to mechanisms involved in the transport of energy sources.

During her thesis, she will perform mutational and reporter fusion experiments on postulated genes involved in dctA regulation. Once the regulator(s) will be characterised, she will try to identify the sRNA involved in this regulation. For this she will perform bioinformatic searches for sRNA candidates that might base-pair with the regulator mRNA(s) and she will test them experimentally.