title: Selective inhibition of tRNATyr transcription by guanosine 3'-diphosphate 5'-diphosphate.
abstract: Guanosine 3'-diphosphate 5'-diphosphate (ppGpp) selectively reduces the synthesis of su+III tRNA from omega 80 psu+III DNA relative to the synthesis of omega 80 RNA in a system in vitro containing DNA and Escherichia coli RNA polymerase holoenzyme as the sole macromolecular components. The response of su+III tRNA synthesis to increasing salt and to temperature in the presence of ppGpp suggests that the nucleotide may reduce the affinity of the enzyme for su+III promoters. The Ki for the selective inhibition of tRNA synthesis by ppGpp is 4 muM in contrast to the value of 150 muM for the inhibition of rRNA synthesis.
mesh_terms: D000643:Ammonium Chloride / Q000494:pharmacology; D004279:DNA, Viral; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000494:pharmacology*; D007700:Kinetics; D009994:Osmolar Concentration; D012343:RNA, Transfer / Q000378:metabolism*; D013696:Temperature; D013698:Templates, Genetic; D014158:Transcription, Genetic / Q000187:drug effects*; D014443:Tyrosine
chemical_list: D004279:DNA, Viral; D006150:Guanine Nucleotides; D000643:Ammonium Chloride; D014443:Tyrosine; D012343:RNA, Transfer; D012321:DNA-Directed RNA Polymerases