Events at initiation of transcription

12
Events at initiatio n of transcrip tion

description

Events at initiation of transcription. Let R = RNA polymerase, P = promoter (closed), and Po= promoter (open). ATP + UTP*. k f. K B. RP. RPo. R + P. k r. Abortive transcripts. ApUp*U. [ApUp*U]. lag. time. Abortive initiation assay. 1. 1. 1. 1. 1. 1. K B k f. K B k f. [R]. - PowerPoint PPT Presentation

Transcript of Events at initiation of transcription

Page 1: Events at initiation of transcription

Events at initiation of

transcription

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Abortive initiation assayLet R = RNA polymerase, P = promoter (closed), and Po= promoter (open)

R + P RP RPoATP + UTP*

ApUp*U

kf

kr

KB

Abortive transcripts

[ApUp*U]

time

lag

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Measure kf and KB from lag time vs. 1/[R]

Lag time

Lag time in abortive initiation assay is inversely proportional to [R].

Lag time = KB kf

1kf

1x +1[R]

1[R]Y-intercept =

kf

1

Slope = KB kf

1

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Effect of wild-type and pc mutant λ repressors on activity of PR & PRM

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Effect of Operator Mutations on Transcriptional Control of PR&PRM

OR1-OR2+OR3- OR1+OR2-OR3+

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Effect of λ-pc mutations on KB and k2

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Architecture of λOR

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Mutations in the Activating Region ofλ Repressor

Glu

Glu

Glu

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Mutations in the δ subunit of RNA polymerase that interfere w/λ repressor-mediated activation of PRM transcription

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Effect of mutations in the δ subunit of RNA polymerase on activator-dependent and independent transcription of the lac

promoter

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A model for interaction of the δ subunit of RNA polymerase with λ repressor

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