Agouron Institute, La Jolla, CA 92037.
Production of light by the marine bacterium Vibrio fischeri and by recombinant hosts containing cloned lux genes is controlled by the density of the culture. Density-dependent regulation of lux gene expression has been shown to require a locus consisting of the luxR and luxI genes and two closely linked divergent promoters. As part of a genetic analysis to understand the regulation of bioluminescence, we have sequenced the region of DNA containing this control circuit. Open reading frames corresponding to luxR and luxI were identified; transcription start sites were defined by S1 nuclease mapping and sequences resembling promoter elements were located.