Functional consequences of T-stem mutations in E. coli tRNA^Thr_UGU in vitro and in vivo

Growth phenotypes and retention of pMAK705 for strains expressing selected tRNA^Thr_UGU variants from the low-copy plasmid (placZACA) that confers kanamycin resistance. Each spot represents equivalent numbers of cells. (A) Growth of E. coli tRNA^Thr_UGU gene knockout strains on plates containing kanamycin (Kan) and chloramphenicol (Clm) at temperatures that are permissive (30°C) or nonpermissive (43°C) for replication of the maintenance plasmid, pMAK705, which confers chloramphenicol resistance. (B) Each strain was continuously grown at 30°C in liquid media containing Kan and the loss of the maintenance plasmid was monitored by testing the initial resistance of each two-plasmid strain to Clm (left panel) and after ∼36 h of growth (right panel).