Those strains that become mucoid upon mucE induction this website are shown in red, while those that remain nonmucoid are shown in black. The red arrow indicates the cutting site of MucA by AlgW. pHERD20T-mucE was conjugated into these non-mucoid CF isolates, and then incubated on PIA

plates containing carbenicillin and 0.1% L-arabinose at 37°C for 24 hours. Mucoid or non-mucoid phenotype was scored based on visual inspection and the amount of alginate production. The quantity of alginate was measured and shown in Table S2. Mutant AlgUs display partial activity resulting in decreased amount of alginate Schurr et al. have reported that second-site suppressor mutations in algU can affect mucoidy [21]. DeVries and Ohman [22] also reported that mucoid-to-nonmucoid conversion in alginate-producing P. aeruginosa is often due to spontaneous mutations Ruxolitinib chemical structure in algT (algU). Recently, Damkiaer et al. [23] showed that point mutations can result in a partially active AlgU. To test whether the activity of AlgU from different CF isolates is affected due to mutation, the CF149 and CF28 algU genes were cloned and over-expressed in PAO1ΔalgU and PAO1miniCTX-P algD -lacZ, respectively. As seen in Figure 6, these constructs retained the ability to promote the transcription of P algD and alginate production. Also, when transposon libraries were screened for mucoid

revertants Coproporphyrinogen III oxidase in CF149 [24] and FRD2, three and five mucoid mutants in CF149 and FRD2, respectively, were identified due to transposon insertion before algU causing the overexpression of algU (data not shown). However, the activity of the mutant AlgU is lower than that of wild type AlgU (Figure 6). In order to determine

whether the mutant AlgU still has the ability to promote mucE transcription, algU genes from CF149 and CF28 were cloned into pHERD20T, respectively, and over-expressed in PAO1 miniCTX-P mucE -lacZ strain. As seen in Figure 2, mutant forms of AlgU were still able to promote mucE transcription, albeit at a reduced level. Figure 6 AlgU with missense mutations induces decreased amount of alginate compared to wild type AlgU. PAO1, CF149 and CF28 algUs were cloned into pHERD20T vector, and conjugated into PAO1ΔalgU and PAO1miniCTX-P algD -lacZ, respectively. Alginate production (μg/ml/OD600) and P algD  activity were measured after culture overnight on PIA plates supplemented with 300 μg/ml of carbenicillin. The values reported here represent an average of three independent experiments with standard error. Characterization of the MucE regulon using iTRAQ analysis In order to determine the effect of mucE expression on the proteome change, we performed iTRAQ proteome analysis via MALDI TOF/TOF. Total protein lysates of PAO1, VE2 (PAO1 with constitutive expression of mucE) and VE2ΔalgU (VE2 with in-frame deletion of algU) were collected and analyzed.