Study of pchP promoter activity in Pseudomonas aeruginosa trough transcriptional fusion

MASSIMELLI, MJ; BEASSONI, PR; DOMENECH, CE; LISA, AT

Pinamar, Buenos Aires

Congreso; XLI Reunión Anual, Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2005

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

Recently, we identified the ORF responsible for phosphorylcholine phosphatase (PChP) activity of P. aeruginosa, named pchP. PChP is involved together with PlcH in the obtention of choline for osmoprotection and growth during infection. Northern blot analysis suggested that pchP is transcribed monocistronically. Using bioinformatic tools the 0,25 kb upstream intergenic region was studied. It showed low homology with prokaryotic promoter consensus sequences. The existence of a promoter in this region, named P92, was confirmed by a lacZ reporter gene fusion. b-galactosidase activity of P92 increased 12 to 20-fold in bacteria grown with choline, betaine and dimethylglycine (DMG) compared with the level observed in bacteria grown with succinate and NH4Cl. The highest P92 activity was observed with DMG as inductor. Lactate, succinate and a-ketoglutarate did not affect P92 activity, but it was inhibited by NH4Cl, glutamine and glutamate. No P92 activity was found in hyperosmolar culture conditions with choline or betaine as osmoprotectants. We conclude that the promotor activity is included in the 0.25 kb fragment located upstream from pchP gene, and it is regulated by choline, its metabolites and by preferential nitrogen sources.