Transcription of the trp operon in Lactococcus lactis is controlled by antitermination in the leader region.
The regulatory functions of the leader region preceding the Lactococcus lactis trp operon have been studied by mutagenesis analysis. This leader presents striking similarity to 'T-box' leaders found upstream of many Gram-positive aminoacyl-tRNA synthetase genes and some amino acid biosynthesis operons, which are controlled by antitermination through interaction of the leader transcript with cognate uncharged tRNA. A region of the L. lactis leader transcript also contains a series of (G/U) AG repeats which, in Bacillus, are involved in the binding of the trp RNA-binding protein (TRAP) which controls trp transcription. A screen was developed for the isolation of regulatory mutants affected in the leader region. All spontaneous mutants contained deletions; point mutations were only obtained after UV-induced mutagenesis. All mutations affected the putative transcription terminator upstream of the trp operon, demonstrating that trp is indeed controlled by transcription antitermination.
Laboratoire de Génètique Microbienne, Institut National de la Recherche Agronomique78352 Jouy-en-Josas CedexFrance.
HéléeGne
H
Frenkiel
Laboratoire de Génètique Microbienne, Institut National de la Recherche Agronomique78352 Jouy-en-Josas CedexFrance.
Jacek
J
Bardowski
Laboratoire de Génètique Microbienne, Institut National de la Recherche Agronomique78352 Jouy-en-Josas CedexFrance.
S Dusko
SD
Ehrlich
Laboratoire de Génètique Microbienne, Institut National de la Recherche Agronomique78352 Jouy-en-Josas CedexFrance.
Alain
A
Chopin
D001483:Base Sequence; D015152:Blotting, Northern; D018388:Codon, Terminator / Q000235:genetics / Q000528:radiation effects; D013294:Lactococcus lactis / Q000235:genetics* / Q000254:growth & development / Q000528:radiation effects; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics / Q000528:radiation effects; D009876:Operon / Q000235:genetics* / Q000528:radiation effects; D012313:RNA / Q000032:analysis; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics / Q000528:radiation effects; D017423:Sequence Analysis, RNA; D014158:Transcription, Genetic / Q000235:genetics* / Q000528:radiation effects; D014364:Tryptophan / Q000096:biosynthesis / Q000235:genetics* / Q000528:radiation effects; D014466:Ultraviolet Rays
D018388:Codon, Terminator; D012313:RNA; D014364:Tryptophan