Figure 9.

Effects of overexpression of yvyD on cell proliferation and ribosome formation. (A) Growth profiles of strain RIK1392 carrying pULI7yvyD in LB medium. Cells were inoculated in LB medium and grown at 37°C with shaking. When the OD₆₀₀ reached ca. 0.1 (indicated by arrow), 1 mM IPTG (final concentration) was added to the culture and the OD₆₀₀ of the culture was monitored: (?) cells treated with IPTG (○) untreated cells (control). (B) Ribosome formation. Sedimentation profiles of sucrose density gradients of IPTG-induced and uninduced cells. Crude cell extracts were prepared from IPTG-induced and uninduced RIK1392 cells and the cell extracts, which were preincubated for 60 min at 37°C, were then sedimented through a 10–40% sucrose gradient as described in the Section Experimental procedures. (C) Western blot analysis of YvyD. Crude cell extracts prepared from wild-type and RIK1392 cells grown in LB medium at 37°C (before [indicated by time 0] and after the addition of IPTG) were subjected to Western blot analysis using the anti-YvyD antibody as described in the Section Experimental procedures. Note that the additional band (shown by dotted arrow) was detected only in the cell extracts of RIK1392 cells.