<i>Escherichia coli nusG</i> mutations that block transcription termination by coliphage HK022 Nun protein

Burova, Elena; Hung, Siu Chun; Chen, John; Court, Donald L.; Zhou, Jianguang; Mogilnitskiy, Grigoriy; Gottesman, Max E.

doi:10.1046/j.1365-2958.1999.01315.x

Cited by 26 publications

(35 citation statements)

References 39 publications

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“…Thus, K106D/K107D and K106A/K107A induce 49% and 79% termination at nutL, respectively, but are entirely inactive at nutR. In this respect, Nun mutants act like host nus and rpoC mutants, which suppress Nun at nutR but have little effect at nutL (2,24). Two factors contribute to the difference between nutL and nutR.…”

Section: Discussionmentioning

confidence: 98%

Transcription Termination by Phage HK022 Nun Is Facilitated by COOH-terminal Lysine Residues

Kim

Gottesman

2004

Journal of Biological Chemistry

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The 109-amino acid Nun protein of prophage HK022 excludes superinfecting bacteriophage by blocking transcription elongation on the chromosome. Multiple interactions between Nun and the transcription elongation complex are involved in this reaction. The Nun NH 2 -terminal arginine-rich motif binds BOXB sequence in nascent transcripts, whereas the COOH terminus binds RNA polymerase and contacts DNA template. Nun Trp 108 is required for interaction with DNA and transcription arrest. We analyzed the role of the adjacent Lys 106 and Lys 107 residues in the Nun reaction. Substitution of the lysine residues with arginine (K106R/ K107R) had no effect on transcription arrest in vitro or in vivo. Nun K106A/K107A was partially active, whereas Nun K106D/K107D was defective in vitro and failed to exclude . All mutants bound RNA polymerase and BOXB. In contrast to Nun K106R/K107R and K106A/ K107A, Nun K106D/K107D did not cross-link DNA template. These results suggest that transcription arrest is facilitated by electrostatic interactions between positively charged Nun residues Lys 106 and Lys 107 and negatively charged DNA phosphate groups. These may assist intercalation of Trp 108 into template.

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Section: Discussionmentioning

confidence: 98%

Transcription Termination by Phage HK022 Nun Is Facilitated by COOH-terminal Lysine Residues

Kim

Gottesman

2004

Journal of Biological Chemistry

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“…Thus, depletion of NusG blocks termination at NUTL, whereas deletion of nusB does not (ref. 24; data not shown). Furthermore, nusA E132K and the rpoC mutations described above inhibit transcription termination at NUTR but not at NUTL (20).…”

Section: Discussionmentioning

confidence: 83%

“…We believe this difference reflects the fact that NUTL is closer to pL than NUTR is to its cognate promoter, pR, rather than a difference between the two NUT sequences. Thus converting NUTL to NUTR did not block Nun termination in nusG mutants (24). In contrast, a nusA mutation inhibited Nun termination at a NUTL located Ϸ1 kb distal to a ptac promoter (ref.…”

Section: Effect Of Nutl and Host Mutations On Translation Repressionmentioning

confidence: 99%

“…Nun termination at NUTR is ablated by mutations in the host nusA, nusB, nusG, or rpoC genes (20,24). These mutations have little effect at NUTL.…”

Section: Effect Of Nutl and Host Mutations On Translation Repressionmentioning

confidence: 99%

“…In contrast, a nusA mutation inhibited Nun termination at a NUTL located Ϸ1 kb distal to a ptac promoter (ref. 24; R. Washburn, personal communication). We asked whether nus and rpoC mutations affected translation inhibition by Nun K106͞107D.…”

Section: Effect Of Nutl and Host Mutations On Translation Repressionmentioning

confidence: 99%

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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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Role of E.coli NusA in Phage HK022 Nun-mediated Transcription Termination

Kim

Washburn

Gottesman

2006

Journal of Molecular Biology

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Escherichia coli nusG mutations that block transcription termination by coliphage HK022 Nun protein

Abstract: SummaryThe Escherichia coli nusG gene product is required for transcription termination by phage HK022 Nun protein at the nutR site in vivo. We show that it is also essential for Nun termination at nutL.

Cited by 26 publications

References 39 publications

Transcription Termination by Phage HK022 Nun Is Facilitated by COOH-terminal Lysine Residues

Transcription Termination by Phage HK022 Nun Is Facilitated by COOH-terminal Lysine Residues

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

Role of E.coli NusA in Phage HK022 Nun-mediated Transcription Termination

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