title: Synthesis of poly(A)+-containing RNA during growth in Escherichia coli relA+ and relA- strains.
abstract: There are very different results on the synthesis of poly(A)+-containing RNA in bacteria. We, therefore, studied the influence of growth and amino acid starvation on the synthesis of poly(A)+-RNA in a relA+ and relA- strains of E. coli. Only the relA+ strains is able to respond to an amino acid limitation by production of ppGpp which causes a strong reduction of stable RNA transcription. During growth we observed significant alterations of the percentage of [3H]-uridine labelled total RNA which bound to poly(U)-sepharose (% poly(A)-RNA). It was mainly influenced by drastic changes of the synthesis of non-polyadenylated stable RNA (rRNA, tRNA) during growth and, therefore, it did not reflect the actual synthesis of polyadenylated mRNA. An amino acid starvation induced in the relA+ strain a stronger and more rapid reduction of the transcription of non-polyadenylated RNA as well as of poly(A)+-RNA than in the relA- strain which did not produce ppGpp under these conditions. Therefore, we conclude that ppGpp inhibited not only the synthesis of the non-polyadenylated stable RNA but also that of poly(A)+-containing mRNA, although the latter was apparently less affected.
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D019286:Endopeptidase K; D010450:Endopeptidases / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D006159:Guanosine Tetraphosphate / Q000378:metabolism; D010636:Phenols / Q000378:metabolism; D011061:Poly A / Q000096:biosynthesis*; D012329:RNA, Bacterial / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000096:biosynthesis*
chemical_list: D000596:Amino Acids; D010636:Phenols; D012329:RNA, Bacterial; D012333:RNA, Messenger; D011061:Poly A; D006159:Guanosine Tetraphosphate; D010450:Endopeptidases; D019286:Endopeptidase K