FIGURE 4.

The defects in 50S ribosomal subunit assembly caused by limited amounts of L20 are enhanced by truncations in its N-terminal tail. Sucrose gradient analysis of ribosomal particles produced from E. coli wild-type strain IBPC5421 and ΔrplT strain IBPC6801 (IBPC5421 background) transformed with the indicated plasmids. Cells were grown in LB medium at 30°C without or with 1 mM IPTG. Absorption profiles were recorded at 254 nm. The absorption peaks of free 30S and 50S ribosomal subunits, 40S ribosomal particles, 70S ribosomes including free couples and monosomes, and polysomes are indicated.