Identification of a major protein upon phosphate starvation of Pseudomonas aeruginosa PAO1.

To understand the physiology of non-differentiating bacteria exposed to nutrient deprivation and stress, various approaches have been employed in combination with detailed analysis of protein synthesis pattern. In this study, separation of proteins from clarified cell extracts of Pseudomonas aeruginosa PAO1 grown under phosphorus limiting conditions was achieved by high resolution two-dimensional gel electrophoresis (2-DE). Limitation of phosphate in the growth medium revealed significant differences in the 2-DE pattern of proteins between phosphate starved cells and an unstarved control. A major protein identified as PstS, a phosphate binding protein of the pts operon was exclusively found on 2-DE gels of phosphate starved bacteria. The identity of protein was established based on the results of Edman degradation, amino acid analysis and mass spectrometry. PstS was also found in other pseudomonads, and therefore, it can be used as a landmark protein in proteomic studies. Additionally, we propose utilizing pstS of pseudomonads for testing bioavailable phosphate from soils and water streams.