Nucleoids were isolated from Escherichia coli B/r cells in steady-stage growth at different rates. The number of RNA chains growing on each nucleoid was estimated from the amount and size of RNAs synthesized by endogenous RNA polymerase. This figure represents the number of RNA polymerase molecules
Preferential ribosomal RNA synthesis in the lysate of Escherichia coli
โ Scribed by Muto, Akira
- Publisher
- Springer
- Year
- 1975
- Tongue
- English
- Weight
- 516 KB
- Volume
- 138
- Category
- Article
- ISSN
- 0026-8925
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โฆ Synopsis
The RNA synthesis in non-viscous lysates containing the intact folded chromosome and cytoplasm fractions prepared from Escherichia coli has been examined in vitro. The RNA synthesis not only by chain extension but also by new chain initiation occurs in this system. While the RNA synthesis by chain extension takes place on the chromosome fraction alone (Pettijohn et al., 1970), an addition of the cytoplasm fraction is necessary for the synthesis by new chain initiations (de novo synthesis). Analyses of the in vitro synthesized RNA by hybridization-competition and by sucrose gradient centrifugation show that 16S and 23S ribosomal RNAs account for about 40% of the total RNA products. The cytoplasm fraction is required for the de novo synthesis of ribosomal RNA at high relative rate. Guanosine tetraphosphate (ppGpp) does not specifically inhibit ribosomal RNA synthesis in this system.
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