SELECTIVE INHIBITION BY TRYPTOPHAN ANALOGUES OF MURINE TOXIN SYNTHESIS IN PASTEURELLA PESTIS

Abstract

Montie, Thomas C. (Albert Einstein Medical Center, Philadelphia, Pa.), and Samuel J. Ajl . Selective inhibition by tryptophan analogues of murine toxin synthesis in Pasteurella pestis . J. Bacteriol. 88: 1467–1475. 1964.—Washed-cell suspensions of Pasteurella pestis , avirulent strain “Tjiwidej,” exhibited a preferential inhibition of toxin synthesis relative to total protein formation, when grown in the presence of various tryptophan analogues. Growth was partially inhibited in the presence of methyl analogues. High concentrations of 5-fluorotryptophan induced slight growth-inhibitory effects. However, toxin production was more sensitive to these levels of the analogue. Growth inhibition appeared not to relate to toxin inhibition. Inhibition of toxin synthesis by analogues was reversed by l -tryptophan and indole. Shikimic acid but not anthranilic acid antagonized the action of 4-methyltryptophan on selective toxin synthesis. The formation of tryptophanless protein accounted for continued protein synthesis in tryptophan-depleted cells. Protein resolved by acrylamide gel electrophoresis from crude cell extracts exhibited two toxic protein bands. The synthesis of one toxin-protein band, the less-mobile of the two, appeared to be associated with the membrane fraction of the cell, and was selectively blocked in cells grown in the presence of tryptophan analogues. Cellular tryptophan levels may determine the quantity and quality of proteins made.