λ nutR mutations convert HK022 nun protein from a transcription termination factor to a suppressor of termination

Robledo, Renato; Gottesman, Max E.; Weisberg, Robert A.

doi:10.1016/0022-2836(90)90226-c

Cited by 38 publications

(43 citation statements)

References 22 publications

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“…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).…”

Section: Hk022 Nun Proteinmentioning

confidence: 99%

“…The hypothesis that a factor exists that acts at BOX-A to inhibit N-mediated antitermination (Patterson et aL, 1994) emerged from two lines of apparently contradictory evidence. First, it was found that point mutations in boxA (boxA5 or boxA 16) inactivate the nut site (Olson et aL, 1984;Robledo et aL, 1990). Second, it was found that deletions that included boxA appear to have little effect on antitermination through Rho-dependent and Rho-independent termination signals (Patterson et aL, 1994;Peltz et aL, 1985;Zuber et aL, 1987).…”

Section: The Inhibitormentioning

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: 99%

Section: The Inhibitormentioning

confidence: 99%

Transcription antitermination: the λ paradigm updated

Friedman

Court²

1995

Molecular Microbiology

128

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“…The 13-kD Nun protein, like the N antitermination protein, binds to the cis-acting nut RNA elements through an arginine-rich binding motif (Chattopadhyay et al 1995). 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.…”

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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“…The bacterial hosts are W3110 or the congenic W3102. Strains carrying a defective cI857 Nam prophage in which the pR-nutR-tR1 region is fused to galETK or to galEoc derivatives are described (20). The pR promoter is activated by thermal denaturation of the cI857 repressor.…”

Section: Methodsmentioning

confidence: 99%

“…The Nun Cterminal amino acid sequence, including the adjacent (K106K107) lysines, is shown. The strains used are described (20). W108 is required for interaction with the DNA template and transcription termination.…”

Section: Inhibition Of N Translation By Nun K106͞107dmentioning

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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λ nutR mutations convert HK022 nun protein from a transcription termination factor to a suppressor of termination

Cited by 38 publications

References 22 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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