Membrane protein synthesis in Escherichia coli: sensitivity to chloramphenicol

Analysis of the labeled proteins of Escherichia coli synthesized in the presence of chloramphenicol (30 or 100 μg/ml) showed: (A) no significant difference in the relative inhibitions of the envelope and cytoplasmic fractions but striking differences in the gel electrophoresis patterns of preparations from chloramphenicol-treated cells versus exponential phase cells; and (B) the average molecular weight of proteins labeled in chloramphenicol (100 μg/ml) was almost half the average of proteins from cells labeled in the absence of chloramphenicol, suggesting that they probably include some incomplete peptides. These results suggest that septation occurs in bacteria by assembly of preexisting envelope proteins in mutants that divide in the presence of high concentrations of chloramphenicol (100 μg/ml).