AndreoNotesLecture1

AndreoNotesLecture1 - -nnAAAA/TA/TA/TTA/TTTTnnAAAAnnn -A/T...

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BCH311H1 Overhead Notes-Lecture 1 Prokaryotic Sigma Factors: Factor Inducer T a r g e t G e n e σ 70 Normal Growth Conditions “Housekeeping” genes σ s Stress, Oxidative, UV radiation Stress genes > 70 σ 32 Heat shock, unfolded proteins Chaperone proteins-folding σ 54 Nitrogen Starvation Metabolism of alternative N sources Q: Which would have the largest Kd? (Kd = dissociation constant, less affinity, higher Kd) Holoenzyme (+ σ ) or Core Enzyme (- σ ) A: Kd Holo > Kd Core Core promoter is comprises both the -35 and -10 consensus sequences (approximately 40 nts upstream from +1 transcription site. Probability of Sequence Occurrence TATAAT (82%/89%/52%/59%/49%/89%, respectively) UP Element: - Upstream sequence –outside the core promoter at approximately 60 nts upstream. -not highly conserved, hence not crucial for transcription -Estrem et al, 1998 derived a consensus sequence
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Unformatted text preview: -nnAAAA/TA/TA/TTA/TTTTnnAAAAnnn -A/T rich region -contacts the C-terminal of -subunit of RNA poly Rho Utilization site = rut site (C-rich region) rRNA = made up of subunits -Dissociation of subunits can occur by decreasing conc. of Mg2+ in medium -motion of a particle in a centrifuge is defined by sedimentation coefficient -Svedberg, S -S increases with the MW of the sedimenting particle (shape also affects rate) -1 S = 10-13 sec -To separate 70S rRNA in E. coli take whole cells, lyse, obtain 70S -70S separated by decreasing Mg2+ into 30S and 50S subunits -30S further separated into 16S + 21 different proteins, 50S further separated into 23S, 5S + 34 different proteins -S values are not additive (ie. 30S + 50S is not equal to 80S) loss of surface area, hence obtain 70S....
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