Figure 5
pgaABCD expression in mutants defective for CsrA-dependent regulation elements and/or PNPase. See Table 1 for the complete list of strains used in these experiments. A Δpnp ΔcsrA double mutant could not be obtained. A. pgaABCD mRNA expression. RNA was extracted from cultures grown in M9Glu/sup to OD600 = 0.8 and analyzed by quantitative RT-PCR as described in Methods. White bars, pnp+ strains; dark grey, Δpnp strains. The “Relative expression” values indicated in the graph are the average of three independent experiments, each performed in duplicate, and standard deviations are shown. The overall p-value obtained by ANOVA is indicated in the graph. Letters provide the representation for posthoc comparisons. According to posthoc analysis (Tukey’s HSD, p < 0.05), means sharing the same letter are not significantly different from each other. B. PNAG production. Crude extracts from overnight cultures were filtered onto a nitrocellulose membrane, and PNAG detection was carried out using polyclonal PNAG specific antibodies as detailed in Materials and Methods. PNAG determination was repeated at least four times on three independent EPS extractions with comparable results; data shown are from a typical experiment.