Replication of the Salmonella Genomic Island 1 (SGI1) triggered by helper IncC conjugative plasmids promotes incompatibility and plasmid loss
Fig 4
Identification of the oriV locus of SGI1.
A. Schematic map of the xis-S003 intergenic region of SGI1 containing oriV. B. Sequence of the oriV region of SGI1. Sequence features are indicated and color-coded as in panel A. The stem-loop of the putative rho-independent transcriptional terminator located downstream of S003 has a calculated free energy (ΔG) of -8.9 kcal/mol (ARNold). C. Schematic representation of the S004-rep locus and translational rep’-’lacZ fusion. The translational lacZ fusion was introduced at position 3,246 after the fifth codon of rep (refer to S6A Fig for details). The relative positions of reverse transcription primer rep_RT as well as PCR primers used to amplify rep and S004 fragments are indicated. The dotted line shows reverse transcription product. D. rep expression is controlled by AcaCD. β-galactosidase assays of the translational rep’-’lacZ fusion in SGI1 Δxis performed in IncC-free cells (-), and in the presence of pVCR94 or pacaCD without (no ara) or with arabinose (+ ara). E. Analysis on a 1.5% agarose gel from an assay to amplify rep and S004 on the rep_RT cDNA. Genomic DNA (gDNA) and RNA samples in the absence of reverse transcriptase (noRT) were used, respectively, as positive and negative PCR controls.
