DNA-DIRECTED INVITRO SYNTHESIS OF PROTEINS INVOLVED IN BACTERIAL TRANSCRIPTION AND TRANSLATION

The in vitro synthesis of elongation factor (EF)-Tu (tufB), the .beta..beta.'' subunits of RNA polymerase, ribosomal proteins L10 and L12 directed by DNA from the transducing phage .lambda.rifd18, EF-Tu (tufA), EF-G and the .alpha. subunit of RNA polymerase directed by DNA from the transducing phage .lambda.fus3 was investigated in a crude and a partially defined protein-synthesizing system. Proteins L10 and L12 are synthesized in the partially defined system almost as well as in the crude system. The synthesis of EF-Tu, EF-G and the .alpha. and .beta..beta.'' subunits of RNA polymerase is far less efficient in the partially defined system. An active fraction that stimulates the synthesis of these latter proteins was obtained by fractionation of a high-speed supernatant on DEAE-cellulose. Because previous studies showed that this fraction (1 M DEAE salt eluate) contains a protein, called L factor, that stimulates .beta.-galactosidase synthesis in vitro, L factor was tested for activity. Although L factor stimulates the synthesis of the .beta..beta.'' subunits, it has little or no effect on the in vitro synthesis of the other products studied. In the present experiments, the ratio of L12/L10 and of EF-Tu (tufA)/EF-G formed is 4-6. These values are consistent with in vivo results. [Escherichia coli was used.].