Specificity determinants and structural features in the RNA target of the bacterial antiterminator proteins of the BglG/SacY family.
Induction of the Bacillus subtilis sacB gene and sacPA operon and Escherichia coli bgl operon is mediated by structurally homologous antiterminators encoded by the sacY, sacT, and bglG genes, respectively. When activated, these proteins prevent early transcription termination at terminators located in the leader regions of the three operons. BglG was previously shown to bind in vitro to an imperfectly palindromic 29-nucleotide RNA sequence located upstream of the terminator and partially overlapping with it [Houman, F., Diaz-Torres, M.R. & Wright, A. (1990) Cell 62, 1153-1163]. Similar motifs, here termed ribonucleic antiterminators (RATs), strongly conserved in sequence and in position, are found in the leader of both sacB and sacPA. Mutations were created in sacB RAT and tested in B. subtilis; this showed that sacB RAT is the target for SacY-mediated induction of sacB and that a stem-loop structure in the mRNA is required for regulatory function. Mutations increasing the similarity of the sacB RAT with those of sacPA or bgl rendered sacB inducible by SacT or BglG, respectively; most of these changes did not strongly affect induction by SacY, suggesting that the nucleotides at these variable positions act as negative specificity determinants.
D001412:Bacillus subtilis / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics*; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D005810:Multigene Family; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D009876:Operon; D010957:Plasmids; D021382:Protein Sorting Signals / Q000235:genetics / Q000378:metabolism; D012329:RNA, Bacterial / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors; D014169:Transformation, Bacterial; D001616:beta-Galactosidase / Q000378:metabolism
D001426:Bacterial Proteins; D021382:Protein Sorting Signals; D012329:RNA, Bacterial; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; C076894:SacY protein, Bacillus subtilis; D014157:Transcription Factors; C064872:antiterminator proteins, Bacteria; D001616:beta-Galactosidase