Interaction of cytoplasmic membrane and ribosomes in Escherichia coli: spectinomycin-induced disappearance of membrane protein I-19.

Incubation of Escherichia coli with spectinomycin caused the disappearance of a major protein from the cytoplasmic membrane. This protein, called "I-19", was not a ribosomal protein. Its disappearance was not a result of the direct action of spectinomycin on the cytoplasmic membrane, but a result of its action on ribosomes. The disappearance was specifically induced by spectinomycin, and other antibiotics such as neomycin, erythromycin, and chloramphenicol had no effect. Although growth was not required for spectinomycin-induced disappearance of protein I-19 from the cytoplasmic membrane, the disappearance was not observed under conditions where protein synthesis was inhibited completely either by the addition of chloramphenicol or by cooling in ice. It is suggested that at least some ribosomes interact with the cytoplasmic membrane and that a modification of the mode of interaction through the action of spectinomycin on ribosomes caused the deletion of membrane protein I-19.