Upstream activating sequence: Difference between revisions

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The property of the ''GAL1-GAL10'' to bind the ''GAL4'' protein is utilised in the [[GAL4/UAS system|GAL4/UAS technique]] for controlled gene misexpression in Drosophila. This is the most popular form of binary expression in ''Drosophila melanogaster'', a system which has been adapted for many uses to make ''Drosophila melanogaster'' one of the most genetically tractable multicellular organisms. <ref>{{cite journal|last1=Wimmer|first1=Ernst A.|title=Applications of insect transgenesis|journal=Nature Reviews Genetics|date=March 2003|volume=4|pages=225-232|doi=10.1038/nrg1021}}</ref> In this technique, four related binding sites between the ''GAL10'' and ''GAL1'' loci in ''Saccharomyces cerevisiae'' serve as an Upstream Activating Sequences (UAS) element through ''GAL4'' binding.<ref>{{cite journal|last1=Duffy|first1=Joseph B.|title=GAL4 system in Drosophilia: A Fly Geneticist's Swiss Army Knife|journal=Genesis|date=2002|volume=34|issue=1-2|pages=1-15}}</ref>. Several studies have been conducted with [[Saccharomyces cerevisiae|''Saccharomyces cerevisiae'']] to explore the exact function of upstream activation sequences, often focusing on the aforementioned ''GAL1-GAL10'' intergenic region [https://www.wikigenes.org/e/gene/e/852307.html].

One study explored the galactose-responsive upstream activation sequence (UAS{{sub|G}}),looking at the influence of proximity to this UAS for nucleosome positioning. Proximity to the UAS was chosen because deletions of DNA flanking the UAS left the nucleosome array unaltered, indicating that nucleosome positioning was not related to sequence-specific histone-DNA interactions. The role of specific regions of UAS{{sub|G}} was analyzed by inserting oligonucleotides with different binding properties, leading to the successful identification of a region responsible for the creation of an ordered array. It should be noted that the sequence identified overlapped a binding site for ''GAL4'' protein, which is a positive regulator for transcription which coincides with the function of upstream activating sequences. t<ref>{{cite journal|last1=Fedor|first1=Martha J.|last2=Lue|first2=Neal F.|last3=Kornberg|first3=Roger D.|title=Statistical positioning of nucleosomes by specific protein-binding to an upstream activating sequence in yeast|journal=Journal of Molecular Biology|date=5 November 1988|volume=204|issue=1|pages=109-127}}</ref>.

Another study looked at the effect of inserting the UAS{{sub|G}} into the promoter region of the glyceraldehyde-3-phosphate dehydrogenase gene (GPD). This hybrid promoter was then utilized to express human immune interferon, a toxic substance to yeast that results in a reduced copy number and low plasmid stability. Relative to the native promoter, expression of the hybrid promoter was induced roughly 150- to 200-fold in the cultures by growth in galactose, induction that wasn't apparent with glucose as the carbon source. When compared to the native GPD promoter, the presence of UAS{{sub|G}} caused the transcriptional activity to remain equivalently enhanced under induced conditions.<ref>{{cite journal|last1=Bitter|first1=Grant A.|last2=Egan|first2=Kevin M.|title=Expression of interferon-gamma from hybrid yeast GPD promoters containing upsream regulatory sequences from the GAL1-GAL10 intergenic region|journal=Gene|date=30 September 1988|volume=69|issue=2|pages=193-207}}</ref>