Fig. 9. YbeY overexpression partially rescues the delayed outgrowth inΔybeX mutant. (A ) A scheme of E. coli open reading frame plasmid library selection experiment for the search of compensatory plasmids rescuing the ΔybeX extended lag phase phenotype. The selection involved sequential regrowth in 25 mL LB medium containing 50 µg/mL Zeocin. Every 12 hours, a 1:100 culture sample was transferred to a fresh LB and incubated for another 12 hours at 37°C with aeration. (B ) Overexpression of YbeY from a pET-based plasmid under the control of taq promoter in the presence of 1 mM IPTG leads to shortened growth lag in the ΔybeX background. (C ) YbeX overexpression from a single copy TransBac library plasmid in the presence of 1mM IPTG has a profound negative effect on the growth of the ΔybeY . The wild-type and ΔybeY strains were conjugated with the backbone TransBac library plasmid (empty),ybeX or ybeY overexpressing single-copy plasmids. The cells were grown in LB liquid medium with tetracycline and 1 mM IPTG. (D-E ) ΔrimM and ΔyjeQ Keio mutant strains were conjugated with the indicated TransBac library plasmids as in panel C. The outgrowth from stationary phase cultures was monitored with aeration in 96-well plates in LB medium at 37°C. The logistic curve fits summarize three to four biological replicates, each comprising a minimum of three technical replicates. Shaded areas represent 95% CI-s.