Effects of penicillin on the synthesis of membrane proteins of Chlamydia trachomatis LGV2 serotype

Cultures of LLC-MK2 cells were infected with Chlamydia trachomatis LGV2 serotype and incubated in medium containing 200 units per ml of penicillin. Forty-eight hours after infection, cells were removed and chlamydiae purified. By Coomassie blue-stained polyacrylamide gels, penicillin-treated chlamydiae showed to be deficient in 60 K and 62 K outer membrane proteins. By using a more sensitive immunoblotting technique, in conjunction with human and animal immune sera containing antibodies specific for the 60 K and 62 K proteins, the synthesis of the 60 K protein turned out to be completely inhibited by penicillin, whereas the 62 K protein seemed to be unaffected. The synthesis of the major outer membrane protein (MOMP), studied with a specific monoclonal antibody by using immunofluorescence and immunoblotting techniques, did not seem affected by penicillin. These data indicate that penicillin interferes with conversion of reticulate body to elementary body of C. trachomatis LGV2 serotype, by affecting the synthesis of the 60 K cysteine-rich outer membrane protein.