Fig. 5. Deletion of the Vs2 region in Hcp1 and Hcp2B impaired the secretion of the corresponding antibacterial effectors.

Antibacterial capability was completely abolished in Tle4- or XmtU-positive donors, suggesting the deficiency of Hcp tube assembly for effector secretion. The plasmid pGEN-MCS was used to express hcp1, hcp1^DelVs2, hcp2A, hcp2A^DelVs1, hcp2B, hcp2B^DelVs1, and hcp2B^DelVs2. Error bars represent the standard deviations from three independent experiments. Asterisks denote competitive outcomes that are significantly different from those obtained with Δtle4 or ΔxmtU (**p < 0.05). a Outcome of growth competition between the indicated donor strains on the x-axis and Δtle4Δtli4. b Growth competition assay for the indicated donor strains on the x-axis and ΔxmtUΔxmtV. c Deletion of Vs2 in Hcp1 impaired effector secretion without affecting Tle4 stability in the cytoplasm. d Vs2 of Hcp2B was required for effector secretion but was not involved in XmtU stability in the cytoplasm. Crp (cyclic AMP receptor protein) is a cytoplasmic protein marker