Open AccessEffects of guanosine tetraphosphate on cell-free synthesis of Escherichia coli ribosomal RNA and other gene products.
Author(s) -
C. Gary Reiness,
HueyLang Yang,
Geoffrey Zubay,
Michael Cashel
Publication year - 1975
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.72.8.2881
Subject(s) - stringent response , ribosomal rna , operon , guanosine , escherichia coli , rna , biochemistry , biology , rna polymerase , transcription (linguistics) , microbiology and biotechnology , 23s ribosomal rna , gene , chemistry , ribosome , linguistics , philosophy
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.