Fig. 6: Plasmid-encoded H-NS-PrfaH regulon mediated the interplay between IncX plasmids in conjugation regulation.

a Deletion of prfaH abolishes the conjugation of pHNYX644∆phns. WT represents the pHNYX644 plasmid. ∆phns∆prfaH represents the pHNYX644 plasmid with deletion of phns and prfaH. ∆phns∆prfaH was complemented by pHSG575-prfaH, pHSG575-phns or pHSG575-prfaH-phns, respectively. ∆phns∆prfaH complemented by pHSG575 was used as the negative control. The statistical analysis was performed using the t-test with Welch’s correction. The p-values are shown when making comparisons with the wild-type (WT). b Plasmid-encoded H-NS inhibits the promoter activity of prfaH. The \({{\rm{\beta }}}\)-Galactosidase assays were carried out with three biological replicates. The statistical analysis was performed using t-test with Welch’s correction. c The effect of plasmid-encoded H-NS and PrfaH on the conjugation of IncX plasmids. The IncX1b(pHN21SC1631T-3) and its mutants are presented in the first group, and the IncX3(pHNYX644) and its mutants are presented in the second group. In the first group, WT represents wild-type IncX1b plasmid; ∆phns represents IncX1b with deletion of phns; ∆phns/P-phns(X1b) represents complementation of ∆phns with pHSG575-phns(IncX1b); ∆phns/P-phns(X3) represents complementation of ∆phns with pHSG575-phns(IncX3); ∆prfaH represents pHN21SC1631T-3 with deletion of prfaH; ∆prfaH/P-prfaH(X1b) represents complementation of ∆prfaH with pHSG575-prfaH(IncX1b); ∆phns/P-prfaH(X3) represents complementation of ∆prfaH with pHSG575-prfaH(IncX3). In the second group, WT represents wild-type IncX3 plasmid; ∆phns represents IncX3 with deletion of phns; ∆phns/P-phns(X1b) represents complementation of ∆phns with pHSG575-phns(IncX1b); ∆prfaH represents pHNYX644 with deletion of prfaH; ∆prfaH/P-prfaH(X1b) represents complementation of ∆prfaH with pHSG575-prfaH(IncX1b). The mating assays were performed to detect the transfer rate of these plasmids. Individual values were obtained from n = 3 independent experiments and represented by dots. The asterisk denotes that the transfer rate fell beneath the detectable threshold (~1\(\times\)10⁻¹⁸). Statistical analyses were performed using t-test with Welch’s correction. The p-values are shown when making comparisons with the wild-type (WT).