INHIBITION OF RNA SYNTHESIS IN FSCHERICHIA COLI BY LEVORPHANOL

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Abstract
The synthetic analgesic, levorphanol, a close structural analogue of morphine, inhibits the synthesis of RNA in E. coli. Inhibition occurs before complete cessation of growth. At a levorphanol concentration of about 1 x 10-3 M, the incorporation of P32 or uracil-C14 into RNA nucleotides is reduced by 80-90%. DNA synthesis continues at an essentially undiminished rate for at least 1 generation, while protein synthesis continues at about 1/2 the rate of a growing control culture. Levorphanol inhibits RNA synthesis in chloramphenicol-treated bacteria and in a methionine-starved "relaxed" mutant, demonstrating that growth and protein synthesis are not required for the effect. Inhibition of polynucleotide synthesis in cell-free systems by levorphanol could not be demonstrated.