1 / 15

Lectures 11/12: Bacterial Adaptation Mechanisms

Lectures 11/12: Bacterial Adaptation Mechanisms. Reading assignments in Text: Lengeler et al. 1999 Text: pages 364-368 Transcription Text: pages 437-452 Transcription mechanisms Text: pages 452-467 Transcription mechanisms Lecture 10 Text: pages 469-483 “Rapid” Enzyme control

grazia
Download Presentation

Lectures 11/12: Bacterial Adaptation Mechanisms

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Lectures 11/12: Bacterial Adaptation Mechanisms Reading assignments in Text: Lengeler et al. 1999 Text: pages 364-368 Transcription Text: pages 437-452 Transcription mechanisms Text: pages 452-467 Transcription mechanisms Lecture 10 Text: pages 469-483 “Rapid” Enzyme control pages 123-126 ATP / NAD(P)H regulation

  2. Lecture Overview Metabolism GROWTH DNA RNA Activity Protein/Enzyme Differentiation Bacterial Diversity Adaptation Mechanisms Change enzyme activities Rapid Slower Make new enzymes

  3. Sensing N and Increasing GS activity Low NH3 GS Sensor UT [Gln / aKeto] P P-UMP (-) AT GS-AMP GS NRII -AMP High activity No FB inhibition ~P NRI More GS protein ? glnA mRNA DNA GS

  4. RNA polymerase / Intrinsic promoter strength Core RNA pol b' b Catalyze RNA (Rif >) 2 x a Proteins Regulators -35 -10 DNA Regulator Protein RNA DNA A/T s +1 TTGACA TAATAT -35 -10 70 “consensus” C C N N R-Pr (open) R-Pr (closed) Kb Kf A/T DNA (rRNA promoters) s R (pol) + Pr (DNA) Intrinsic promoter strength = (Kb)x(Kf)

  5. Regulating intrinsic promoter strength P UT [Gln / aKeto] (-) (-) NRII Drives open DNA complex ATP DNA GS NRII -24 -12 NRI RNA ~P NRI~P C N C N -120 Enhancer Helper protein DNA bending Integration Host Helper (IHF) Nitrogen regulators NRI, NRII, sigma-54 High Kb, Kf ~0

  6. Lac operon promoter: low Kb, good Kf +glucose -glucose RNA +Lactose cAMP Activation by cAMP Receptor “CRP” TTGACA TAATAT X X X mismatch -Lactose s -35 -10 -35 -10 LacI = Repressor 70 Kb = 0 expected “consensus” High Kb observed Kf ~ 0 N N N C C C N N N C C C DNA lac operon genes Inducer +Lactose Make Inducer “quick release / quick start” DNA lac operon genes “Toe-clip”

  7. Why regulate? E. coli People soil water sewer Glucose + Galactose “Allolactose” Glucose-b-1,6-Galactose H. s. mutants “LacZ” birth 0 Where is Lactose? Rare food, ~50% calories of milk Glucose-b-1,4-Galactose What is Lactose? Digestion? LacZ = b-galactosidase What is the inducer? When does E. coli see Lactose?

  8. Lac operon Quiz Repressor O LacZ Permease Acetylase IPTG = “gratuitous inducer” Allolactose (Original Jacob and Monod 1961) LacA enz. LacZ enz. E. coli genome - IPTG +IPTG - IPTG +IPTG low High low High Wild type Z Y A I lacI- null lacI-null & F’ lacI lacI-S lacI-S & F’ lacI lacOC lacZ- null lacA- null lacZ- null &F’ lacOC lacZlacA-null lacI-S &F’ lacOC lacZ lacA

  9. Lac operon Quiz Answers Repressor O LacZ Permease Acetylase IPTG = “gratuitous inducer” Allolactose (Original Jacob and Monod 1961) LacA enz. LacZ enz. E. coli genome - IPTG +IPTG - IPTG +IPTG low High low High Wild type Z Y A I lacI- null High High High High lacI-null & F’ lacI low High low High low low low lacI-S low lacI-S & F’ lacI low low low lacI-S dominance low High lacOC High High High zero zero lacZ- null low High, but low +lactose low lacA- null High zero zero High High low High lacZ- null &F’ lacOC lacZlacA-null High lacI-S &F’ lacOC lacZ lacA High High High From F’ plasmid

More Related