Probing for Promoters with Luciferase-Transposons

The union of transposon mutagenesis and reporter gene fusion technologies has created a very powerful tool for analyzing gene expression. Transposable elements, such as phage Mu and Tn5 , are able to move within a DNA molecule or from one DNA molecule to another, and can randomly integrate into the bacterial chromosome or plasmids. Transposition into a coding sequence can disrupt gene function and produce a null mutant phenotype. If the null mutant exhibits an obvious phenotype, then it is possible to screen for specific mutations on selective media. Once a mutant is isolated, the responsible gene can be identified by mapping the transposon insertion site. However, not all genes encode an obvious phenotype or readily assayable product. By coupling transcription or translation to an easily assayed reporter gene, it is possible to monitor expression of any gene, even if its phenotype is not known a priori .