Cycloheximide inhibition of amino acid uptake and protein biosynthesis by chloroplasts incubated in vitro

Abstract

Cycloheximide is known to be a strong inhibitor of protein biosynthesis in systems with 80 S ribosomes whereas systems with 70 S ribosomes such as isolated mitochon­ dria of isolated chloroplasts are unaffected by this antibiotic. Surprisingly, using a system of isolated chloroplasts from young pea leaves, cycloheximide and N-ethylmale- imide inhibited protein synthesis as measured by incorporation of (14C)-leucine into protein. Experiments performed in several conditions showed that the inhibitory effects of cycloheximide, N-ethylmaleimide and 2,4-dinitrophenol could be produced by an interference with and ATP-dependent transport of one or more amino acids into chloro­ plasts.