Figure 6. Phr*_LS20 pentapeptide inhibits conjugation in an opp dependent manner.

A. Effects of synthetic Phr* peptide on conjugation in the wild type and an opp deficient background. Conjugation efficiencies of pLS20cat were determined at late exponential growth phase using as recipient strain PKS7, and as donor either strain PKS11 (wild type, black bars) or PKS98 (oppA, grey bars). Diluted overnight grown cultures of donor cells were split in two, and Phr*_LS20 pentapeptide was added to a final concentration of 6 µM to one of the cultures and equal volume of the peptide buffer to the other. B. Conjugation kinetics of pLS20cat and pLS20phr. Conjugation kinetics was determined as described in Materials and Methods using PKS7 as recipient strain and PKS14 (pLS20cat) or PKS117 (pLS20phr) as donor strains. t = 0 corresponds to the end of the exponential growth phase. Both donor strains contain an ectopic copy of rco_LS20 under the IPTG inducible P_spank promoter at the chromosomal amyE locus. Overnight cultures of donor cells were grown in the presence of 1 mM IPTG and diluted in fresh pre-warmed LB medium without IPTG. C. Conjugation kinetics of pLS20cat after re-dilution of the donor cell culture. Conjugation kinetics using PKS7 and PKS11 as recipient and donor strains, respectively, was determined as described in Materials and Methods with the following modification. Overnight cultures were diluted, grown until late exponential growth phase (OD₆₀₀ = 0,8), and diluted again (to OD₆₀₀ = 0.05) before starting the experiment. B and C. t = 0 corresponds to the end of the exponential growth phase.