SmR1 (GenBank: CP002039, ) as shown in Additional file 1, Figure S3. All of these putative promoter regions, with the exception of phaP2, were assayed for DNA binding by His-PhbF. DNA band-shift assays showed that click here purified His-PhbF was able to bind specifically to these eleven promoter regions (Figure 1 and results not shown) but not to the unrelated nifB promoter (Additional file 1, Figure S4) indicating that the protein is active. The apparent dissociation constants observed varied from 150 nM (phaP1) to 450 nM (phbF). Figure 1 The DNA-binding assays of purified His-PhbF from H. seropedicae SmR1 to the promoter regions of phaP1, phbF, dskAphbC, fadBphbA, phbCphbB and H_sero3316phaB were performed as described in Material and Methods. DNA promoter regions used in the assays are indicated by vertical selleck kinase inhibitor black arrow heads and numbers indicate base position related to the translation start of each gene. Panel A: DNA labeled with [32P]. Lanes 1 to 5 indicate increasing amounts
of purified His-PhbF (0, 280, 570, 860 or 1100 nM). Panel B: Fluorescent labeled DNA. Lanes 1 to 8 indicate increasing amounts of purified His-PhbF (0, 62, 125, 250, 500, 750, 1000 or 1250 nM). Protein concentrations were calculated assuming His-PhbF as a tetrameric protein. These twelve promoter regions (including phaP2, additional file 1, Figure S3) were also analyzed in silico using the MEME program  which indicated the sequence TG[N]TGC[N]3GCAA as a probable DNA-binding motif for PhbF (Figure 2A). A similar sequence (CTGC[N]3GCAG) Inositol monophosphatase 1 GANT61 was also described in R. sphaeroides FJ1 as the DNA-binding site for the regulator PhaR . Both sequences show two highly conserved triplets (TGC and GCA) which seem to be essential for DNA-binding of R. sphaeroides PhaR . Figure 2 Panel A: Sequence logo representing the consensus sequence of pha promoter
regions identified by the program MEME motif discovery tool. In the y axis the information is represented in bits indicating the nucleotide frequency in the sequence at that position. The putative consensus sequence probably recognized by PhbF is indicated. Panel B: DNase I-protection footprinting assay was carried out as described in Material and Methods. The non-coding strand of the phbF promoter was used as a probe. The assays were in the absence (lane 1) or presence 155 (lane 2) or 312 nM (lane 3) of the purified His-PhbF tetramer. Lane P indicates the undigested promoter region. The DNA sequencing reaction is indicated in lanes A, C, G, and T. The region showing protection from DNaseI digestion is indicated by **. The probable σ70 promoter is indicated by *. Numbers indicate base position corresponding to the translation start codon. To verify if the TG[N]TGC[N]3GCAA sequence is important for DNA-binding of H.