In this sense, one might also speculate that the hypothetical proteins identified as non variant in the two LY2874455 order strains may have functions associated to the general physiology of C. pseudotuberculosis, when grown in minimal medium. The most up-regulated proteins were observed in the extracellular proteome of the C231 strain, including two cell envelope-associated proteins [62], namely the major secreted (mycoloyltransferase) protein

PS1 (10-fold up-regulated), and the S-layer protein A (8-fold up-regulation) (Figure 3). This may be indicative of differences on cell envelope-related activities in the two C. pseudotuberculosis strains, such as nutrient acquisition, protein export, adherence and interaction with the host [63]. Dumas et al. [49] compared the exoproteomes of Listeria monocytogenes strains of different virulence P505-15 groups, and found that altered expression (up- or down-regulation) of a protein related to the bacterial cell wall could be a marker of specific virulence phenotypes.

Additionally, surface associated proteins have been GF120918 chemical structure shown to undergo phase and antigenic variation in some bacterial pathogens, and ultimately affect the infectivity potential of different strains [50]. Comparative analyses of corynebacterial exoproteomes Recent studies attempted to characterize the extracellular proteomes of other pathogenic (C. diphtheriae and C. jeikeium) and non-pathogenic (C. glutamicum and C. efficiens) corynebacterial species [17, 37, 64, 65]. All these studies

used 2D-PAGE to resolve the extracellular proteins of the different corynebacteria, and PMF by MALDI-TOF-MS was the method of choice in most of them for protein identification [17, 37, 64, 65]. Figure 4 shows the numbers of proteins identified in the exoproteomes of all strains studied, in comparison to the numbers obtained in the present study for C. pseudotuberculosis. Despite one study with the strain R of C. glutamicum, many which reports identification of only two secreted proteins [65], all the corynebacterial strains had somehow similar numbers of extracellular proteins identified, ranging from forty-seven in C. jeikeium K411 to seventy-four in C. diphtheriae C7s(-)tox-. Importantly, the fact that we have identified in this study 93 different exoproteins of C. pseudotuberculosis, through the analysis of two different strains, means that our dataset represents the most comprehensive exoproteome analysis of a corynebacterial species so far. Figure 4 Comparative analysis of corynebacterial exoproteomes. Numbers of extracellular proteins identified in previous corynebacterial exoproteome analyses [17, 37, 69, 70] in comparison to those identified in this study with the two strains of C. pseudotuberculosis.