Promoter region deletions

The presence of an enhancer sequence may cause as much as 100- to 1000-fold increase in the rate of transcription as compared with the same transcriptional emit from which the enhancer has been deleted. A surprising fact is that enhancers as far as 1 -2 kbp upstream or even far downstream of the promoter and in either of the two possible orientations are effective. range conformational alterations in DNA. Alternatively, they might contain points of entry for RNA polymerase or for an initiation factor that could move along the DNA to the promoter region. However, the synthetic DNA molecule shown in Fig. 28-14 contains two copies of an enhancer in opposite orientations in one strand but none in the other strand.354 The... 

In healthy plants, the basal level of GUS expression remained unaffected when the promoter was deleted from -900 to —318. However, GUS activity decreased dramatically when the promoter was deleted to -222. GUS activity decreased to virtually undetectable levels when the promoter was deleted to -150. Further deletion to -75 slightly increased the level of constitutive expression to about the level of the —222 deletion. These results suggest that there may be an element in the —318 to —222 region which is important for non-specific transcription. Further, there may be a negative element that suppresses transcription around the —150 region that is lost when the promoter is deleted to —75. 

The methods used for the evaluation of regulation of gene expression are too numerous to be described in detail here. They include Northern analysis to determine levels of a particular mRNA, nuclear run on to determine whether an increase in mRNA is due to an increase in the rate of transcription, and promoter deletion analysis to identify specific elements in the promoter region responsible for the control of expression. Of much current interest is the use of microarrays that permit the study of the expression of hundreds to thousands of genes at the same time. Reverse transcriptase-polymerase chain reaction and RNase protection assay techniques are used to amplify and quantitate mRNAs, while the electrophoretic mobility shift assay is used to measure binding of a transcription factor to its specific DNA consensus sequence. 

The 5 sequence is not essential for accurate transcription initiation. When the region extending from the 5 end of the gene (that is, the part that would normally be considered to be the promoter) is deleted, RNA synthesis is carried out just as efficiently as on the native gene. The new 5 end of the transcript is complementary to whatever sequences take the place of the natural ones. Furthermore, initiation is only affected when sequences within the 5S rRNAgene are disrupted. The molecular explanation for this phenomenon is as follows ... 

Ankyrin 8 Ankyrin and spectrin deficiency Ankyrin gene deletion Promoter region mutations Ankyrin Stuttgart (329 2-nt deletion) Ankyrin Einbeck (572 1-nt Insertion) Ankyrin Marburg (797/798 4-nt deletion) Ankyrin Bovenden (1436Arg—Her) Others AD orAR Mild to severe 50%-60%... 

Figure 2.9. Luciferase reporter gene assay/promoter deletion analysis. Cells are transfected with the CYP1A1 promoter reporter (luciferase) constructs in which the promoter region is increasing deleted. The cells are then treated with benzo[a]pyrene (an inducer of CYP1A1), and cells are harvested 24-48hr later and luciferase activity is measured. Promoter deletion analysis revealed enhancer element between -1140 and -1029. Contained within this region is xenobiotic response element (XRE) to which the aryl hydrocarbon receptor (AHR) binds.

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