Determination and Analysis of the Putative AcaCD-Responsive Promoters of Salmonella Genomic Island 1

摘要: The integrative genomic island SGI1 and its variants confer multidrug resistance in numerous Salmonella enterica serovariants several Proteus mirabilis Acinetobacter strains. is mobilized by the IncA/C family plasmids. exploits not only conjugation apparatus of plasmid, but also utilizes plasmid-encoded master regulator AcaCD to induce excision formation transfer-competent form, which a key step horizontal transfer SGI1. Triggering occurs via AcaCD-dependent activation xis gene expression. binds Pxis an unusually long recognition sequence. Beside promoter, upstream regions four additional genes, S004, S005, S012 S018, contain putative AcaCD-binding sites. Furthermore, encodes AcaCD-related activator, FlhDCSGI1, has no known function. Here, we have analysed functionality promoter proved their either or FlhDCSGI1. Moreover, provide evidence that both activators act on same binding site FlhDCSGI1 able complement acaCD deletion plasmid R16a. We determined transcription start sites for AcaCD-responsive promoters showed orf S004 expressed probably from different codon than predicted earlier. Additionally, expression S003 PS004 was ruled out. examined here lack obvious -35 box profile consistent with class II-type pathway. Although role additionally AcaCD/FlhDCSGI1-controlled genes and/or maintenance yet clear, conservation whole region suggests existence some selection functionality.