Escherichia coli mutations that block transcription termination by phage HK022 Nun protein

Robledo, Renato; Atkinson, Brent L.; Gottesman, Max E.

doi:10.1016/0022-2836(91)90104-e

Cited by 43 publications

(53 citation statements)

References 20 publications

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“…Selected as inhibitors of Nun termination at NUT-R, surprisingly, the latter mutations have no effect on Nun termination at NUT-L. Identification of a host mutation, rpoClO0, that interferes with Nun-directed termination suggests a role for the I~' subunit of RNA polymerase in transcription termination (Robledo et aL, 1991).…”

Section: Hk022 Nun Proteinmentioning

confidence: 98%

“…Mutations in Escherichia coil nus genes that cause a failure in N-mediated antitermination also affect Nun-mediated termination (Robert et aL, 1987;Robledo et aL, 1990). Moreover, other mutations in these nus genes have been isolated that reduce Nun action but not N action (Robledo et aL, 1991). Selected as inhibitors of Nun termination at NUT-R, surprisingly, the latter mutations have no effect on Nun termination at NUT-L.…”

Section: Hk022 Nun Proteinmentioning

confidence: 99%

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Transcription antitermination: the λ paradigm updated

Friedman

Court²

1995

Molecular Microbiology

128

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Section: Hk022 Nun Proteinmentioning

confidence: 98%

Section: Hk022 Nun Proteinmentioning

confidence: 99%

Transcription antitermination: the λ paradigm updated

Friedman

Court²

1995

Molecular Microbiology

128

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“…In contrast to N, which suppresses transcription termination promoter-distal to nut, Nun provokes termination downstream of these elements in both the p L and p R operons (Robert et al 1987;Robledo et al 1990;Sloan and Weisberg 1993). Nun-induced transcription termination is inhibited by mutations in nut or in the trans-acting Escherichia coli proteins NusA, NusB, NusE, and NusG (Robert et al 1987;Robledo et al 1990Robledo et al , 1991Baron and Weisberg 1992;E. Burova, S.C. Hung, and M.E.…”

mentioning

confidence: 99%

The Nun protein of bacteriophage HK022 inhibits translocation of Escherichia coliRNA polymerase without abolishing its catalytic activities

Hung¹,

Gottesman²

1997

Genes Dev.

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Bacteriophage HK022 Nun protein blocks transcription elongation by Escherichia coli RNA polymerase in vitro without dissociating the transcription complex. Nun is active on complexes located at any template site tested. Ultimately, only the 3 -OH terminal nucleotide of the nascent transcript in an arrested complex can turn over; it is removed by pyrophosphate and restored with NTPs. This suggests that Nun inhibits the translocation of RNA polymerase without abolishing its catalytic activities. Unlike spontaneously arrested complexes, Nun-arrested complexes cannot be reactivated by transcription factor GreB. The various complexes show distinct patterns of nucleotide incorporation and pyrophosphorolysis before or after treatment with Nun, suggesting that the configuration of RNAP, transcript, and template DNA is different in each complex.

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“…Thus, Nun K106͞107D did not suppress polarity at distal terminators activated by polar ochre mutations in galE (Table 1). In contrast, N fully suppresses polarity in these galEoc mutant fusions (9).…”

Section: Nun C-terminal Mutations That Eliminate Transcription Terminmentioning

confidence: 92%

“…Arrest in vitro is stimulated by, but does not depend on, the host NusA, NusB, NusE, and NusG factors. In vivo, mutations in these nus genes block Nun termination in the pR operon (9).…”

mentioning

confidence: 99%

Phage HK022 Nun protein represses translation of phage λ N (transcription termination/translation repression)

Kim¹,

Zhou²,

Wilson³

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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The N-terminal arginine-rich motif of phage HK022 Nun protein binds to NUT sequences in phage nascent transcripts and induces transcription termination. Interactions between the Nun C terminus and RNA polymerase as well as the DNA template are required for termination. We have isolated Nun C-terminal point and deletion mutants that are unable to block transcription. The mutants bind NUT RNA and inhibit translation of the N gene. Thus HK022 excludes both by terminating transcription on the phage chromosome and by preventing translation of the essential N gene. Like N autoregulation, translation repression by Nun requires host RNaseIII deficiency (rnc) or a mutation in the RNaseIII processing site (rIII) located between NUTL and the beginning of the N coding sequence. Our data support the idea that Nun bound at NUTL causes steric interference with ribosome attachment to the nearby N coding sequence. Two models, Nun acting alone or in complex with host proteins, are discussed.

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Escherichia coli mutations that block transcription termination by phage HK022 Nun protein

Cited by 43 publications

References 20 publications

Transcription antitermination: the λ paradigm updated

Transcription antitermination: the λ paradigm updated

The Nun protein of bacteriophage HK022 inhibits translocation of Escherichia coliRNA polymerase without abolishing its catalytic activities

Phage HK022 Nun protein represses translation of phage λ N (transcription termination/translation repression)

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