Effects of guanosine tetraphosphate on cell-free synthesis of Escherichia coli ribosomal RNA and other gene products.
AUTOR(ES)
Reiness, G
RESUMO
A cell-free system derived from E. coli is described in which mature-sized 16S and 23S ribosomal RNAs (rRNA) are synthesized at a high relative rate, comprising 17-25% of the total transcription. The addition of guanosine tetraphosphate (ppGpp) to this system results in up to a 5-fold selective inhibition of rRNA accumulation. This effect is exerted at the level of synthesis rather than degradation. It is concluded that ppGpp, which is produced in large amounts by E. coli during amino-acid deprivation, could mediate the decrease in rRNA synthesis that accompanies such deprivation. The expression of other genes has also been investigated. No selective reduction of transfer RNA synthesis by ppGpp is observed. The trp and lac operons are found to be stimulated at the transcriptional level by the presence of this nucleotide. It is hypothesized that ppGpp interacts with the RNA polymerase in such a manner as to alter the affinity of the enzyme for promoters in an operon-specific fashion.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=432882Documentos Relacionados
- MACROMOLECULAR SYNTHESIS IN CELL-FREE PREPARATIONS FROM ESCHERICHIA COLI1
- INDUCED ENZYME SYNTHESIS IN CELL-FREE PREPARATIONS OF ESCHERICHIA COLI12
- SYNTHESIS OF PURINE INTERMEDIATES BY A CELL-FREE EXTRACT OF ESCHERICHIA COLI
- CELL-FREE PROTEIN SYNTHESIS: THE ASSOCIATION OF VIRAL RNA AND E. COLI RIBOSOMES*
- Effects of temperature and lipophilic agents on poliovirus formation and RNA synthesis in a cell-free system.
