Dependence of cytoplasmic on mitochondrial protein synthesis in K. Lactis CBS 2360. I. Biochemical analysis.

In the "petite negative" yeast Kluyveromyces lactis (strain CBS 2360) growth is inhibited by the same Erythromycin concentrations on fermentable and non-fermentable carbon sources. The minimal inhibitory concentrations of Erythromycin does not affect respiration, but completely inhibits total aminoacid incorporation by the cells in conditions in which permeability effects can be ruled out. The effect of the antibiotic on the "in vitro" protein synthesis by cytoplasmic and mitochondrial systems shows that inhibition is effective only at the mitochondrial level. Results suggest that the inhibition of growth and of total protein synthesis is a consequence of the inhibition of mitochondrial protein synthesis.