The increases and decreases in abundance
were generally consistent across techniques for most proteins (22/44 comparisons and a further 11/44 where the iTRAQ ratios were not statistically significant for inclusion). 9/44 were detected as changing by iTRAQ 2-DLC/MS-MS but were apparently not changing on 2-DE gels, while only 2/44 comparisons PRN1371 nmr showed opposite changes. These last two groups contained many proteins that appear as multiple protein ‘spots’ on 2-DE gels (e.g. ArcB) and thus it is difficult to gauge the overall abundance of those proteins by the gel-based approach. Discussion This study compared proteome profiles of 3 P. aeruginosa strains to identify candidate proteins that may be specific to the acute, transmissible CF strain AES-1R. Proteins identified in the AES-1R isolate may reflect adaptations specific to the environmental niche of this organism and that could provide a colonization GSK126 concentration advantage in the CF lung. A number of virulence determinants differed in abundance between strains, including secreted factors, siderophore and pigment producing enzymes, and oxidative stress response proteins. P. aeruginosa is
known to produce a number of secreted virulence factors including toxins, proteases and binding proteins, many of which are under QS regulation [36, 37]. AES-1R protein profiles displayed elevated abundances of Seliciclib clinical trial chitinase ChiC, chitin-binding protein CbpD, and putative hemolysin (PA0122), while the major secreted protease elastase LasB was increased in virulent PA14. Microarray studies have shown increased expression of hcnB and cbpD in mucoid P. aeruginosa compared to non-mucoid [38]. Since AES-1R is non-mucoid, it is possible that these proteins
are more abundant in CF isolates irrespective of mucoidy when compared to non-CF strains. Comparisons of a chronic, rather than acute, CF isolate with PAO1 also showed increased cbpD gene expression [25]. Putative hemolysin (PA0122) is highly expressed in non-mucoid CF clinical isolates and binds oxidised low-density lipoprotein from human serum present in the CF lung [39, 40]. Increased chitinase production may provide AES-1R with an enhanced ability to degrade lung connective tissues [41]. We also observed elevated abundance in AES-1R of PasP (PA0423), a small protease that cleaves Fluorometholone Acetate collagens and a virulence determinant in P. aeruginosa-associated corneal infections [42]. PasP has been described as an immunogen in 4 CF patient sera [43]. Importantly, it must be noted that our data reflect intracellular levels of these predominantly secreted proteins, suggesting either altered expression or impaired secretion. We were able to detect higher elastase and total protease activities for AES-1R compared to PAO1, while total hemolysin activity was approximately the same. Similar to the proteomics data, we observed reduced elastase activity for AES-1R compared to PA14. P.
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