Genome-wide analytical approaches using semi-quantitative expression proteomics for aromatic hydrocarbon metabolism in Pseudomonas putida F1.

Pseudomonas putida F1 can degrade aromatic hydrocarbons to intermediate products of the tricarboxylic acid cycle. To determine key induced proteins and enzymes required for degradation of toluene, ethylbenzene, benzene, p-cymene, and p-cumate, we performed comprehensive proteome analysis using a combination of 1-D SDS-PAGE and LC-MS/MS in cells grown in the presence of each aromatic hydrocarbon. Semi-quantitative analysis using protein content calculated from the exponentially modified protein abundance index (emPAI) was performed for each proteome data set, and the resulting data were compared. Of 5250 known proteins in P. putida F1, 1733-2368 expressed proteins were identified. All of the key enzymes in the degradation pathways were identified. Additionally, the proteins induced by the aromatic hydrocarbons, regulators, and transporters were also found. Using K-means clustering analysis of the proteome data sets, substrate-specific induced proteins were characterized, ranging from 62 to 164 in number. The functions of most of these proteins were not unknown in relation to the metabolism of aromatic hydrocarbons. These results suggest that the approaches used here are ideal as a primary investigation of the various physiological characteristics of bacterial cells.