The Drosophila Eve gene has a complex promoter containing multiple binding sites for four transcription regulators: Bicoid, Hunchback, Giant, and Krüppel. Bicoid and Hunchback are activators of Eve transcription, whereas Giant and Krüppel repress Eve transcription The Eve promoter contains modules that control expression in various stripes. You construct a reporter gene that contains the DNA 5 kb upstream of the Eve gene, so that this reporter contains the stripe 3 module, the stripe 2 module, the stripe 7 module, and the TATA box, all fused to the LacZ reporter gene (which encodes the β-galactosidase enzyme), . This construct results in expression of the β-galactosidase enzyme in three stripes, which correspond to the normal positions of stripes 3, 2, and 7
a- By examining the overlap of sites on the stripe 2 module, as depicted in Figure B, what is the biological effect of having some of the transcription regulator binding sites overlap?
b-. You make two mutant versions in which several of the binding sites in the Eve stripe 2 module have been deleted, as detailed in items (i) and (ii) below. Refer to Figure B for the positions of the binding sites. (Note, however, that because many of the binding sites overlap, it is not possible to delete all of one kind of site without affecting some of the other sites.) Match the appropriate mutant condition with the most likely pattern of Eve expression shown in Figure C. Explain your choices.
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