Membrane Protein Synthesis in Micrococcus lysodeikticus and Selective Effect of Chloramphenicol

Abstract

Micrococcus lysodeikticus cytoplasmic membranes labeled with [14C]arginine plus [14C]-threonine were prepared and subjected to mild washing treatments to fractionate membrane proteins. Polyacrylamide gel electrophoresis of total membranes, in the presence of sodium dodecyl sulfate, results in the separation of 28–30 bands of labeled protein. Three peaks of protein show higher specific radioactivity than the others. Chloramphenicol at 100 μg/ml inhibits the incorporation of labeled precursors into membrane proteins by 45–70%, some of them being more affected by the antibiotic. From all available results, we suggest that the partial inhibitory effect shown by this antibiotic could be due to the existence of specific biosynthetic sites for some membrane proteins, which are differently affected by chloramphenicol.