Action of cycloheximide on amino acid metabolism in Saccharomyces elipsoideus

Abstract

In proliferating Saccharomyces elipsoideus, cycloheximide inhibited the incorporation of l-[ 14C 5]valine, [1- 14C]glycine and l-[ 14C 5]glutamic acid into the cellular protein whereas it increased the intracellular level of pool amino acids ( e.g., glutamic acid, glutamine, glycine and serine). With enzyme preparations of the same organism, the antibiotic prevented transfer of l-[ 14C 6]leucyl-soluble RNA into ribosomal protein and in addition, the amino acid incorporation into aminoacyl-soluble RNA. Cycloheximide stimulated the accumulation of exogenous l-[ 14C 5]glutamic acid and its metabolic products in the soluble cell fraction, but depressed that of [1- 14C]glycine and related substances. In resting yeast, cycloheximide stimulated the incorporation of [6- 14C]glucose and [1- 14C]acetate into most of the pool amino acids and Krebs-cycle intermediates, but inhibited 14C incorporation into the insoluble cell fraction. Interconversions of pool amino acids were also affected by cycloheximide since in proliferating yeast more glutamine and less proline were formed from glutamic acid and more serine was formed from glycine. Cycloheximide altered the incorporation of nucleotides labelled with [8- 14C]adenine into the nucleic acids, which was inhibited in proliferating yeast and stimulated in resting yeast. Synthesis de novo of purines from [1- 14C]glycine was also inhibited by cycloheximide. Trehalose concentration and the incorporation of acetate and glucose carbon atoms into trehalose were inhibited by cycloheximide.