What happens if region 1-100 is removed from the Gal4p sequence?

Can someone verify the validity of my statements? (This topic is extremely confusing to me)

A) What happens if region 1-100 is removed from the Gal4p sequence?
Gal4p is a protein encoded by the GAL4 gene and the entire protein consists of a total of 881 amino acids. Section 1-98 of the entire Gal4 protein is called the “DNA binding domain.” In order for transcription activation to occur, this domain basically recognizes and binds itself to the trans-activating domain (located from around amino acid 148 all the way to 881.) So for question one, if this domain is completely removed from the sequence, transcription activation is not allowed to occur.

B) Why would no transcription occur in gene GAL1 if the entire GAL3 gene is deleted?
Gal3 is a protein encoded by the GAL3 gene, and when bound to galactose, the gal3p molecule undergoes a conformational change that allows it to interact with the gal4/gal80 complex. So if the entire GAL3 gene is deleted, there won’t be any Gal3 protein available to regulate complex, which means that transcription of the GAL1 gene would not be able to occur.  (in GAL3 mutants- the GAL structural genes are not active in the presence of glucose)

C) What happens if Gal80 is blocked from interacting with Gal3p?
 Transcription activation occurs when galactose interacts with Gal3 protein (GAL3p). So, like the last problem, if there is interference in Gal3p’s ability to interact with the Gal80/Gal4 complex- GAL1 transcription cannot occur. In this case there is a mutation that blocks the Gal80 gene from interacting with GAL3p.


D)  Why does a deletion of one of the 4 UASg elements cause a reduction in transcription in the GAL1 gene?
A deletion of one of the four UASG elements would reduce transcription of the GAL1 gene.  UASg stands for Upstream Activation Sequence for the galactose region and it is a control region in the gene that controls the transcription of LAC1. 4 UASg elements are required by all genes in order to have a strong transcription and they require the binding of a specific protein to activate transcription.  So a deletion of one element will weaken and therefore reduce transcription.

E) Why is there a reduction in transcription when a point mutation on the GAL1 promoter alters the sequence of TATA box?
TATA box usually has sequence 5'-TATAAT-3' . For this problem, Transcription of the GAL1 gene would be reduced as a result of a point mutation in this sequence. This goes for any sort of mutation involving the TATA box. In general, any sort of mutation in the TATA box would cause a reduction in the relevant gene.