Bacterial luciferase activity and the intracellular redox pool in Escherichia coli

In this study, we analyzed the activity of a bacterial luciferase (LuxAB of Vibrio fischeri) expressed under the control of a consensus-type promoter, lacUV5, in Escherichia coli, and found that activity declines abruptly upon entry into the stationary growth phase. Since this decline was reproducibly observed in strains cultured in various growth media, we refer to this phenomenon as ADLA (Abrupt Decline of Luciferase Activity) and define the time point when activity begins to decline as T (0). Because the levels of luciferase proteins (LuxA and LuxB) remained constant before and after T (0), ADLA cannot be due to the repression of luciferase gene expression. Further analyses suggested that a decline in the supply of intracellular reducing power for luciferase was responsible for ADLA. We also found that ADLA was alleviated or did not occur in several mutants deficient in nucleoid proteins, suggesting that ADLA is a genetically controlled process involved in intracellular redox flow.