putida do not harbor an AHL quorum sensing system, however they possess PpoR indicating that it is likely to be part of the core genome of this species. We have shown that PpoR binds AHLs and that it is highly conserved in P. putida; and this in our view represents the important novel finding of our study., In addition we believe that we are in a position to conclude that the results obtained using our strain represent

what occurs GSK458 datasheet in P. putida strains (including the ones which only have PpoR and do not contain a complete AHL QS system). Future studies will be directed towards understanding the regulation of target genes in response to exogenous AHLs in certain P. putida strains and also possibly endogenous AHLs in strains

which harbor an AHL QS system. Methods Bacterial strains, plasmids and media All strains, plasmids and primers used in this study are listed in Tables 1 and 4. P. putida [21–24] and E. coli strains were grown in Luria-Bertani (LB; [25]) medium at 30 and 37°C respectively. P. putida strains were also grown in M9 minimal medium [26] supplemented with 0.3% casamino acids (M9-Cas) at 30°C. Agrobacterium tumefaciens NTL4 (pZLR4) was grown in AB medium [27] selleck kinase inhibitor at 28°C. Antibiotics when required were supplemented at the following concentrations: ampicillin, 100 μg/ml; kanamycin, 100 μg/ml (Pseudomonas) or 50 μg/ml (E. coli); nalidixic acid, 25 μg/ml; tetracycline, 10 μg/ml (E. coli) or 40 μg/ml (Pseudomonas); and gentamicin, 10 μg/ml (E. coli) or 40 μg/ml (Pseudomonas). Transcriptional fusion constructs for ppoR FHPI clinical trial promoter in pMP220 [28] were made as follows: a 598-bp fragment containing the ppoR promoter region was amplified from P. putida RD8MR3 genomic DNA with the primers 16orpF

and 16orpR using Vent DNA polymerase (New England Biolabs) following supplier’s instructions, cloned in pBluescript (Stratagene) yielding pBS1 and verified by DNA sequencing (Macrogen Inc., Korea). The ppoR promoter was removed as a KpnI-XbaI fragment from pBS1 and cloned in pMP220 yielding pPpoR1. Similarly, a 318-bp fragment was amplified from P. putida WCS358 genomic DNA using primers 358orpromF mafosfamide and 358orpromR and cloned in pBluescript yielding pBS2. The ppoR promoter was removed as KpnI-XbaI fragment from pBS2 and cloned in pMP220 yielding pPpoR2. To clone ppoR gene in pQE30, a 721-bp fragment containing the entire ppoR gene of P. putida KT2440 was amplified using primers KT_PpoRf and 4647R1 and cloned in pBluescript yielding pBS3. The ppoR gene was removed as SphI-HindIII fragment and cloned in pQE30 in the correct reading frame yielding pQEPpoR. To clone ppoR in pBBR [29], the 749-bp fragment containing the entire ppoR gene was amplified using P. putida WCS358 genomic DNA as the template using primers 358_PpoRf and 358_PpoRr and cloned in pBluescript yielding pBS4. ppoR gene was excised from pBS4 using XbaI-KpnI and cloned into pBBR mcs-5 yielding pBBRPpoR.