title: cis-acting sequences of Bacillus subtilis pyrG mRNA essential for regulation by antitermination.
abstract: Expression of the Bacillus subtilis pyrG gene, which encodes CTP synthetase, is repressed by cytidine nucleotides. Regulation involves a termination-antitermination mechanism acting at a transcription terminator located within the 5' untranslated pyrG leader sequence. Deletion and substitution mutagenesis of a series of pyrG'-lacZ transcriptional fusions integrated into the B. subtilis chromosome demonstrated that only the terminator stem-loop and two specific 4- to 6-nucleotide RNA sequences were required for derepression of pyrG by starvation for cytidine nucleotides. The first sequence, GGGC/U, comprises the first four nucleotides at the 5' end of the pyrG transcript, and the second, GCUCCC, forms the first six nucleotides of the 5' strand of the terminator stem. All of the nucleotides lying between the two required RNA sequences can be deleted without loss of regulation. We propose that an as-yet-unidentified regulatory protein binds to these two RNA segments and prevents termination of transcription in the pyrG leader region when intracellular CTP levels are low.
authors.affiliation: Department of Biochemistry, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: Qi
authors.initials: Q
authors.lastname: Meng
authors.forename: Robert L
authors.initials: RL
authors.lastname: Switzer
mesh_terms: D020121:5' Untranslated Regions / Q000737:chemistry / Q000235:genetics; D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D019731:Carbon-Nitrogen Ligases / Q000737:chemistry / Q000235:genetics*; D004742:Enhancer Elements, Genetic; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000737:chemistry* / Q000235:genetics; D013728:Terminator Regions, Genetic; D014158:Transcription, Genetic
chemical_list: D020121:5' Untranslated Regions; D012333:RNA, Messenger; D019731:Carbon-Nitrogen Ligases; C019951:CTP synthetase