global-reg - lac promoter relative to catabolite repression...

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A Couple of Examples of Global Regulation I. Catabolite repression - CAP regulon A. misnomer, since the CAP protein is an activator B. catabolite-sensitive operons C. cAMP made by adenylate cyclase ( cya gene) - ATP cAMP - decrease energy level - increased cAMP D. Linked to phosphotransferase system (PTS) Fig. 13.2 - Adenylate cyclase::II Glc ~P is active - if no glucose is available, the higher level of II Glc ~P E. CAP/CRP ( crp gene) is usually an activator, but can also be a repressor F. CRP-cAMP is the active form that binds specific DNA sequence G. CRP-cAMP has affinity for RNA-Pol (alpha subunits) H. CRP regulon genes have poor upstream elements that usually increase RNA-Pol binding I. CRP-regulated genes usually are regulate by other regulators, so at least 2 levels of regulation needed (web of regulation) J. How can you construct constitutive “ON” mutations for catabolite repression? (2) K. Notice the effects of mutations in the
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Unformatted text preview: lac promoter relative to catabolite repression II. Heat shock response Fig. 13.13 A. Both a regulon and stimulon with >30 genes B. Not only induced by heat - other stresses, too. C. Heat Shock Proteins (HSPs) - highly conserved among most organisms D. HSPs have normal functions 1. Chaperones - help fold proteins: GroE, DnaK, DnaJ, GrpE 2. Proteases - Lon, Clp E. Role of sigma-32 ( 32 ) - major; sigma-24/sigma-E ( 24 / E ) - minor F. sigma-32 = rpoH G. 15x induced protein after heat shock, but not so much mRNA H. Role of DnaK (HSP - sigma-32-regulated) 1. binds to misfolded proteins 2. during heat shock is occupied with misfolded proteins 3. during normal growth binds to sigma-32 a. prevents sigma-32 from binding to promoters b. causes sigma-32 to be degraded I. Heat shock response is transient - cell will accommodate higher temperature...
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