Modulation of PRM Activity by the Lambda PR Promoter in Both the Presence and Absence of Repressor

Fong, Raymond Shiaw-Ching; Woody, Scott; Gussin, Gary N.

doi:10.1006/jmbi.1993.1432

Cited by 17 publications

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“…Second, in agreement with the suggestions of others (1), the results shown in this paper indicate that the 434 repressor also activates P RM transcription by releasing an "inhibitory" effect of RNA polymerase bound at the strong promoter P R . The homologous repressor employs identical strategies in stimulating transcription from P RM (6,10,11,12,14,16,18).…”

Section: Discussionmentioning

confidence: 99%

“…In the case of the repressor, an open complex at P R does not appear to affect binding of RNA polymerase to P RM (10). Instead, the RNA polymerase-P R complex inhibits the rate of isomerization of a closed complex at P RM to an open complex (6,11,26). Hence in O R , open complex formation at P R and that at P RM are not mutually exclusive.…”

Section: Discussionmentioning

confidence: 99%

“…Relief of promoter interference by the repressor also leads to an increase in the rate of isomerization (6,11,26). Although the precise kinetic mechanism by which the 434 repressor stimulates transcription from 434 P RM has not yet been determined, several lines of evidence indicate that the 434 repressor enhances the formation of closed complexes by recruiting RNA polymerase to the P RM promoter (28).…”

Section: Discussionmentioning

confidence: 99%

“…Evidence suggests that the O R 2-bound repressor of each phage activates transcription initiation by directly contacting the 70 subunit of the P RM -bound RNA polymerase (16,18). Studies of bacteriophage indicate that, in addition to activating P RM transcription by directly contacting RNA polymerase, the repressor also activates transcription indirectly by relieving interference with an RNA polymerase bound at P R (6,10,11). Interestingly, in phage, formation of an open complex at the P R promoter does not prevent RNA polymerase from binding at P RM but rather impairs isomerization of the RNA polymerase-P RM closed complex to an open complex (6,10).…”

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confidence: 99%

“…Studies of bacteriophage indicate that, in addition to activating P RM transcription by directly contacting RNA polymerase, the repressor also activates transcription indirectly by relieving interference with an RNA polymerase bound at P R (6,10,11). Interestingly, in phage, formation of an open complex at the P R promoter does not prevent RNA polymerase from binding at P RM but rather impairs isomerization of the RNA polymerase-P RM closed complex to an open complex (6,10). These findings lead to the suggestion that formation of an open complex at the P R promoter interferes with formation of a similar complex at P RM .…”

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Mutually Exclusive Utilization of P _R and P _RM Promoters in Bacteriophage 434 O _R

Koudelka

2000

J Bacteriol

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Establishment and maintenance of a lysogen of the lambdoid bacteriophage 434 require that the 434 repressor both activate transcription from the P RM promoter and repress transcription from the divergent P R promoter. Several lines of evidence indicate that the 434 repressor activates initiation of P RM transcription by occupying a binding site adjacent to the P RM promoter and directly contacting RNA polymerase. The overlapping architecture of the P RM and P R promoters suggests that an RNA polymerase bound at P R may repress P RM transcription initiation. Hence, part of the stimulatory effect of the 434 repressor may be relief of interference between RNA polymerase binding to the P RM promoter and to the P R promoter. Consistent with this proposal, we show that the repressor cannot activate P RM transcription if RNA polymerase binds at P R prior to addition of the 434 repressor. However, unlike the findings with the related phage, formation of RNA polymerase promoter complexes at P RM and at P R apparently are mutually exclusive. We find that the RNA polymerase-mediated inhibition of repressor-stimulated P RM transcription requires the presence of an open complex at P R . Taken together, these results indicate that establishment of an open complex at P R directly prevents formation of an RNA polymerase-P RM complex.Each lambdoid bacteriophage contains a right operator (O R ) region on its chromosome that is at the center of a complex regulatory circuit responsible for governing the phage's choice between lytic and lysogenic development. Proper regulation of transcription initiation from the divergently oriented P R and P RM promoters that lie within the O R region is crucial to the lysis-lysogeny decision. In each phage, the activities of these promoters are regulated, in part, by the binding of the bacteriophage repressor to three recognition sites that partially overlap the P R and P RM promoters. In the absence of the repressor, the P RM promoter is virtually inactive and RNA polymerase preferentially initiates transcription at the P R promoter. During an infection or induction of a lysogen, continued activity of the P R promoter drives the phage to develop lytically. If the phage is to develop or maintain the lysogenic state, there must be exclusive expression of P RM over P R .To perform its role in the lysis-lysogeny decision, the repressor must bind to each of the three binding sites or operators within O R with different affinities and act both as transcriptional activator of P RM and as repressor of P R . In a developing or existing lysogen, the repressor binds with highest affinity to two sites, O R 1 and O R 2. In this configuration, the repressor molecule bound at O R 2 activates transcription from the P RM promoter. This event leads to expression of the cI gene that encodes the repressor, which is the sole protein responsible for maintenance of the lysogenic state. This binding configuration also permits the repressor to concurrently inhibit transcription initiation from P R and in doing so preven...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Mutually Exclusive Utilization of P _R and P _RM Promoters in Bacteriophage 434 O _R

Koudelka

2000

J Bacteriol

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Transcription Activation Parameters at

Zhang

Reeder

Schleif

1996

Journal of Molecular Biology

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Repression of Transcription Initiation at 434 PR by 434 Repressor: Effects on Transition of a Closed to an Open Promoter Complex

Koudelka

2001

Journal of Molecular Biology

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Modulation of PRM Activity by the Lambda PR Promoter in Both the Presence and Absence of Repressor

Cited by 17 publications

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Mutually Exclusive Utilization of P _R and P _RM Promoters in Bacteriophage 434 O _R

Mutually Exclusive Utilization of P _R and P _RM Promoters in Bacteriophage 434 O _R

Transcription Activation Parameters at

Repression of Transcription Initiation at 434 PR by 434 Repressor: Effects on Transition of a Closed to an Open Promoter Complex

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Modulation of PRM Activity by the Lambda PR Promoter in Both the Presence and Absence of Repressor

Cited by 17 publications

References 0 publications

Mutually Exclusive Utilization of P R and P RM Promoters in Bacteriophage 434 O R

Mutually Exclusive Utilization of P R and P RM Promoters in Bacteriophage 434 O R

Transcription Activation Parameters at

Repression of Transcription Initiation at 434 PR by 434 Repressor: Effects on Transition of a Closed to an Open Promoter Complex

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Mutually Exclusive Utilization of P _R and P _RM Promoters in Bacteriophage 434 O _R

Mutually Exclusive Utilization of P _R and P _RM Promoters in Bacteriophage 434 O _R