Disease relevance of lacR

• Molecular cloning, transcriptional analysis, and nucleotide sequence of lacR, a gene encoding the repressor of the lactose phosphotransferase system of Lactococcus lactis [1].
• Transcriptional fusions of both the lac operon promoter and the lacR promoter to the luxAB genes of Vibrio fischeri were used to investigate the regulation of expression of both promoters [2].

High impact information on lacR

• Transcription of lacR, into a 1.2-kilobase monocistronic messenger, is repressed approximately 5-fold during growth on lactose [1].
• The presence of lacR on a multicopy plasmid resulted in the decrease of lactose phosphotransferase system activity, whereas only on lactose a decrease (25%) of growth rate was observed [1].
• Nucleotide sequence analysis of the lacR gene showed the presence of an open reading frame of 861 base pairs [1].
• In vivo bioluminescence assays demonstrated that lacR negatively regulates the lac operon and also autoregulates itself [2].
• Genes for the lactose-specific PEP-PTS proteins, phospho-beta-galactosidase and tagatose 6-phosphate pathway enzymes are encoded by a single 8 kb operon, lacABCDFEGX, and there is a divergently transcribed lacR repressor gene [2].

Biological context of lacR

• The lacR promoter was demonstrated to be a particularly strong promoter, being approximately four times more efficient than the lac operon promoter [2].

References