Differential expression of genes on the Enterococcus faecalis plasmid pCF10 in the presence and absence of prgU

Efficient horizontal gene transfer of the conjugative plasmid pCF10 from Enterococcus faecalis depends on the expression of its Type 4 Secretion System (T4SS) genes, controlled by the PQ promoter. The PQ promoter is strictly regulated, partially to limit cell toxicity caused by overproduction of PrgB, a T4SS adhesin. PrgU plays an important role in regulating this toxicity by decreasing PrgB levels. PrgU has an RNA-binding fold, prompting us to test whether PrgU exerts its regulatory control through binding of prgQ transcripts. We used a combination of in vivo methods to quantify PrgU effects on prgQ transcripts at both single cell and population levels. Comparison of transcript levels in parental and prgU deletion strains using RNAseq