Use of transcriptional fusions to monitor gene expression: a cautionary tale

Gene fusions are frequently used to facilitate studies of gene expression and promoter activity. We have found that certain reporter genes can, themselves, influence promoter activity. For example, the commonly used luxAB reporter genes can activate or repress transcription from a subset of promoters, generating data apparently at odds with those obtained with other reporter genes. These effects are probably related to an intrinsically curved DNA segment in the 5' coding sequence of the luxA gene. Thus, caution must be observed when one is interpreting results obtained with a single reporter gene system such as luxAB.