TIM207 strain exhibits differentially phosphorylated proteins As MG207 is Selleck Tariquidar a phosphatase presumed to be associated with signaling, it was predicted that absence of this protein might alter the phosphorylation status of some M. genitalium proteins. To determine this, and also to identify some of the differentially phosphorylated proteins, we performed 2-D gel analysis of proteins from G37 and TIM207 strains and stained them with Pro-Q Diamond (Figure 3A and C) and Sypro Ruby stains (Figure 3B and D). While the total proteins
stained with Sypro Ruby showed similar profiles for G37 and TIM207 strains, the phosphoproteins stained with Pro-Q Diamond displayed different profiles for these strains. These differences in phosphorylation appear not due to differences in the growth of the wild type (G37) and mutant (TIM207) strains as they showed no significant differences (data not shown) in growth. Further, the differences do not appear due to variability
in viability because both strains exhibited similar viability at the time of harvest (CX-6258 solubility dmso Additional file 1: Figure S1). Figure 3 2D gel analysis of M. genitalium total and phosphorylated proteins. Total protein from M. genitalium strains (G37 wild type and TIM207 mutant) were separated in 2D gels and stained with Pro-Q Diamond and Sypro Ruby for the detection of phosphoproteins (gels A and C) and total proteins (Gels B and SYN-117 solubility dmso D), respectively. Protein spots circled and numbered are the ones subjected to mass spectrometry analysis. Protein spots shown in large circles denote the putative high molecular weight proteins showing differential phosphorylation. The sizes (kDa) of protein markers are shown on the right and direction of the first runs are shown by arrows. The predominant difference was noticed to be at the high molecular
weight (HMW) areas which are shown in large circles (Figure 3A and C). As can be seen, the gels from G37 showed relatively dense and larger stained areas as compared to gels from the TIM207 strain, suggesting PtdIns(3,4)P2 that some HMW proteins are less phosphorylated in TIM207 strain. However, these dense areas have shown no corresponding protein spots in Sypro Ruby stained gels, thus indicating that these areas do not represent real proteins but represent some artifacts. Therefore, we focused only on well separated and differentially phosphorylated proteins. These included two proteins (shown in circles 1 and 2) which showed relatively dense staining in the gels of G37 strain but were weaker in the gels of TIM207 strain, and three proteins (shown in circles 3, 4 and 5) that showed stronger staining in the gels of TIM207 strains but were weaker in the gels of G37. To identify the differentially phosphorylated proteins, we subjected the protein spots 1–5 to mass spectrometry (Additional file 2: Table S1).