Figure 4.

The Presence of DsbA in Target Cells Is Essential for Intoxication by the Periplasmic-Acting Effectors Ssp2 and Ssp4

(A) Recovery of target strains S. marcescens Db10 Δssp4Δsip4 and Δssp4Δsip4ΔdsbA1ΔdsbA2, following co-culture with wild-type Db10 (WT), the Δssp4 effector mutant, or sterile media alone (none) as attacker. Individual data points are overlaid with the mean ± SEM (n = 4).

(B and C) As in (A), except that recovery of the Δssp2Δrap2A mutant (B) or the Δrhs2ΔrhsI2 mutant (C), with or without additional ΔdsbA1ΔdsbA2 deletions, following co-culture with the wild-type and the cognate effector mutant was determined.

(D) Growth of wild-type (WT) and ΔdsbA mutant E. coli BW25113 carrying the vector control (+VC, pBAD18-Kn) or plasmids directing the expression of Ssp4 fused with an N-terminal OmpA signal peptide (+_SP-Ssp4, pSC1234) or _SP-Ssp4 with Sip4 (+_SP-Ssp4,Sip4, pSC861).

(E) Growth of wild-type and ΔdsbA mutant E. coli BW25113 when carrying plasmids directing the expression of Ssp2 fused with an OmpA signal peptide (+_SP-Ssp2, pSC138) or _SP-Ssp2 with Rap2a (+_SPSsp2,Rap2a, pSC144). For (D) and (E), strains were grown in LB with 0.002% arabinose. Points show mean ± SEM (n = 4).

(F) Recovery of control (ΔlacA::Kn^R) or ΔdsbA (ΔdsbA:: Kn^R) E. coli BW25113 following co-culture with wild-type or T6SS-inactive (ΔtssE) S. marcescens Db10.

See also Figure S3.