The inactivation of mgoA has previously been shown to result in defects in mangotoxin production and considerably reduced virulence [15]. However, a putative RBS for mgoA could not be located using the consensus sequences published

to date. Finally, insertional mutagenesis of the mgoD gene, which contains a putative RBS at -6 (ATGGAG), resulted in the inactivation of a conserved hypothetical protein that is 94% identical to Psy_5012. A conserved-domain analysis of the hypothetical amino acid sequence EPZ004777 of MgoD revealed sequence similarity to Polyketide_cyc2, a polyketide cyclase/dehydrase and lipid transporter domain, from amino acids 20 to 158. The e-values were 1e-17 (Specialized BLAST-NCBI) and 1.6e-23 (Pfam). The genetic organisation of the mgo operon and complementation of insertional mutants To define the mgo operon and determine its genetic organisation and co-transcription, reverse-transcription PCR (RT-PCR) experiments were performed (Figure 2). The total GSK1838705A cost DNA and RNA from wild-type UMAF0158 grown in PMS minimal medium at 22°C were used, and the RT-PCR primers were designed to anneal between the ORFs. The total DNA was used as an amplification control, and the cDNA derived from the mRNA was used to detect the transcripts of genes belonging to the putative mgo operon.

To confirm the co-transcription of mgoB, mgoC, mgoA and mgoD, we amplified the connecting

areas between the sequential ORFs of the putative mgo operon (Figure 2A). Sequences within ORF2 and mgoB were also amplified to determine their mRNA transcripts (Figure 2A, B). Our results indicated that ORF2 and the upstream region and mgoB and the downstream region were amplified. However, there was MycoClean Mycoplasma Removal Kit no amplification of the inter-genetic region upstream of mgoB. These results suggest that the transcriptional unit is mgoB, mgoC, mgoA and mgoD (Figure 2B). The lack of amplification between ORF2 and mgoB supports the presence of a putative promoter in this DNA sequence. Figure 2 Characterisation of the mgo operon: A) diagram of the location of the amplified region obtained during the RT-PCR experiments. The molecular size and gel lanes are indicated. Lanes 2 and 5 have two molecular sizes: lane 2 shows 306 bp, and line 5 shows 360 bp in section B; lane 2 shows 401 bp and lane 5 shows 568 bp in section C. The putative mgo operon involved in mangotoxin production by Pseudomonas syringae pv. syringae UMAF0158 is illustrated by grey boxes, and the upstream ORF is indicated by a white box. Each gene studied in this study was given a specific name. B) The PCR products obtained from the RT-PCR experiments that used as templates genomic DNA and mRNA derived from wild-type UMAF0158 after 48 h of incubation at 22°C on liquid PMS minimal medium.