the gene of interest is in the plasmid, bracketed by P-elements, short inverted repeats, which facilitate insertion into the genome.

In Chapter 8 we learned that the P-genes encode P-transposase which will catalyze the integration of the P-elements into the genome.

The sequence of interest is chosen because it is thought to contain a gene encoding an enhancer (or multiple enhancers). The sequence is linked to a weak promoter (that can’t initiate transcription alone) and a reporter gene (in this case the lacZ gene). If there are enhancers present in the sequence then transcription will be initiated, therefore β-Galactosidase will be produced through the expression of the lacZ gene.

These E. coli are plated on X-gal to detect the production of β-Galactosidase.

The fragment can be made smaller and smaller to identify a more specific location of the enhancer gene.

What is the identity of the transcription-factor proteins that bind to the enhancer?