13BIS101S2013GeneRegulLect13-1

Galactose proteins gal4 gal80 gal3 rnapii tata box

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Unformatted text preview: XII XIII MEL1 GAL4 XVI GAL4 GAL80 XIII Blocks GAL4 Galactose + inducer GAL3 GAL80 Blocks GAL80 BIS101­001, Spring 2013—Genes and Gene Expression R.L. Rodriguez ©2013 BIS101­001, Spring 2013—Genes and Gene Expression R.L. Rodriguez 40 UAR Between GAL 1 and GAL10 Between Gal1 and Gal10, there is a 356 base pair region that Between contains 8 UAS sequences. contains Gal 4 Gal 4 (Galactose) GAL10 TBP RNAPII TBP TATA RNAPII TATA (Glucose) Gal 80 GAL10 GAL10 Gal 80 TATA TATA (Galactose + Glucose) CRP TATA GAL1 GAL1 TATA GAL1 CRP BIS101­001, Spring 2013—Genes and Gene Expression R.L. Rodriguez ©2013 BIS101­001, Spring 2013—Genes and Gene Expression R.L. Rodriguez 41 Summary of Gal Gene Regulation Components: Genes: GAL7, 10, 1, 4, 80, 2, MEL1 (GAL3 and 5 are involved but not regulated by Genes: GAL7, galactose). galactose). Proteins: GAL4, GAL80, GAL3 RNAPII, TATA-box binding factor (TBF), catabolite Proteins: repression protein (CRP) induced by glucose. repression DNA Binding Sites: UASs and TATA box. Effector Molecules: Galactose and Glucose. Interactions: 1. RNAPII/TATA = no mRNA 2. GAL4/UAS/TBF/RNAPII/TATA = mRNA 3. GAL4/UAS/GAL80 = no mRNA 4. Inducer+GAL3/GAL80 (blocks GAL4/GAL80 interaction) = mRNA 5. CRP/GAL4 = no mRNA Mutations: 1. gal4- (uninducible, UN) 1. gal4 2. gal80- (constitutive, C) gal80 3. gal80s (UN, insensitive to inducer) gal80 (UN, 4. gal4((81) (Constitutive, can not bind GAL80) 4. gal4 81) (Constitutive, 5. gal4(pro26) (UN, can not bind UAS, corrected by Zn ion) gal4 6. gal3- (uniducible, UN) 6. gal3 BIS101­001, Spring 2013—Genes and Gene Expression R.L. Rodriguez ©2013 BIS101­001, Spring 2013—Genes and Gene Expression R.L. Rodriguez 42 Sequence of Events in Gal Regulation Galactose Galactose [I] [80/3] [80/4] [4/TBF] = [mRNA] No Galactose [I] [80/3] [80/4] [4/TBF] = no mRNA Gal + Glucose [I] [80/3] [80/4] [CRP/4] [4/TBF] = no mRNA Conclusions: 1. GAL4 is an activator protein 2. GAL80 is an antagonist of GAL4 3. I (inducer) + GAL3 are antagonists of GAL80 4. CRP is a glucose-induced antagonist of GAL4 What is the nature of the GAL4-UAS interaction? BIS101­001, Spring 2013—Genes and Gene Expression R.L. Rodriguez ©2013 BIS101­001, Spring 2013—Genes and Gene Expression R.L. Rodriguez 43 Nature Gal4/UAS binding GAL4 regulates transcription by binding to UASs. The UASs GAL4 are found in the promoter regions of all the GAL genes regulated by GAL4. The UASs act similarly, but not identically, to mammalian enhancer sequences (i.e., modular, orientation independent, act at a distance to activates transcription). Some kind of DNA binding mechanism must be invoked to explain the action of UASs and enhancers. UAS: Sequence analysis of the UASs show that they are Sequence highly conserved. UASgal are 17 base pair palindromic DNA highly gal sequences with dyad symmetry sequences 5’-C G G GC A C G T G C A C CA TG 5’ G T T C C A C G T G C A C G G G CC- = may be C G BIS101­001, Spring 2013—Genes and Gene Expression R.L.Rodri...
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