title: Gene inactivation in Lactococcus lactis: branched-chain amino acid biosynthesis.
abstract: The Lactococcus lactis subsp. lactis strains isolated from dairy products are auxotrophs for branched-chain amino acids (leucine, isoleucine, and valine), while most strains isolated from nondairy media are prototrophs. We have cloned and sequenced the leu genes from one auxotroph, IL1403. The sequence is 99% homologous to that of the prototroph NCDO2118, which was determined previously. Two nonsense mutations and two small deletions were found in the auxotroph sequence, which might explain the branched-chain amino acid auxotrophy. Nevertheless, the leu genes from the auxotroph appear to be transcribed and regulated similarly to those from the prototroph.
authors.affiliation: Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique, Jouy en Josas, France.
authors.forename: J J
authors.initials: JJ
authors.lastname: Godon
authors.forename: C
authors.initials: C
authors.lastname: Delorme
authors.forename: J
authors.initials: J
authors.lastname: Bardowski
authors.forename: M C
authors.initials: MC
authors.lastname: Chopin
authors.forename: S D
authors.initials: SD
authors.lastname: Ehrlich
authors.forename: P
authors.initials: P
authors.lastname: Renault
mesh_terms: D000595:Amino Acid Sequence; D000597:Amino Acids, Branched-Chain / Q000096:biosynthesis*; D001483:Base Sequence; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004926:Escherichia coli / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D013294:Lactococcus lactis / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D010957:Plasmids; D014158:Transcription, Genetic; D014169:Transformation, Bacterial
chemical_list: D000597:Amino Acids, Branched-Chain; D004269:DNA, Bacterial