CHROMOSOMALLY DIRECTED PROTEIN SYNTHESIS

Abstract

The ability of chromatin, isolated from various tissues of the pea plant, to support DNA-dependent RNA synthesis is enhanced in the presence of the RNA polymerase of E. coli. Such chromatin-dependent RNA synthesis was coupled to a messenger RNA-dependent ribosomal protein synthesis system, the latter also derived from E. coli. The material synthesized by the ribosomal system under the direction of chromatin isolated from developing pea cotyledons includes a protein characteristic of such cotyledons, the pea-seed reserve globulin. Chromatin of pea buds, which do not synthesize pea seed globulin in vivo, does not support the synthesis of such globulin by the isolated ribosomal system. Hence the control of genetic activity characteristic of the living cell is, to an appreciable extent, preserved in the isolated chromatin. This control is exerted by the histone of the chromosome. Thus, the removal of histone from pea bud chromatin, in which the genes for globulin synthesis are repressed, yields DNA which supports globulin synthesis.