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The initiation of both transcription and translation occurs in membrane-associated nucleoid of E. coli without the addition of cytoplasmic fraction. Initiation of translation, however, is stimulated by adjunction of S 165. Our results suggest that the system is limited in synthesizing F-met-tRNA. The capacity of nucleoid-extracted ribosomes to form initiation complexes is only slightly higher than that of supernatant ribosomes. RNA synthesis is partially rifampicin-sensitive, which implies that initiation of new chains takes place in our system.

The induction of beta-galactosidase and alkaline phosphatase by the nucleoid of Escherichia coli was studied. Only the membrane-associated form was active in the presence of S 30. The induction of beta-galactosidase showed an absolute requirement for the inducer and was enhanced by cyclic AMP and cyclic GMP. Further-more, in our hands, the synthetic activity of the membrane-associated nucleoid proved to be far higher than that of the soluble system described by Zubay. Our results suggest that membrane shield the structure which is necessary for the integrity of the initiation step of both transcription and translation.