| Autor: |
Bernardo, Lisandro M. D., Johansson, Linda U. M., Solera, Dafne, Skärfstad, Eleonore, Shingler, Victoria |
| Předmět: |
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| Zdroj: |
Molecular Microbiology; May2006, Vol. 60 Issue 3, p749-764, 16p, 1 Diagram, 2 Charts, 8 Graphs |
| Abstrakt: |
The RNA polymerase-binding protein DksA is a cofactor required for guanosine tetraphosphate (ppGpp)-responsive control of transcription from σ70 promoters. Here we present evidence: (i) that both DksA and ppGpp are required for in vivoσ54 transcription even though they do not have any major direct effects on σ54 transcription in reconstituted in vitro transcription and σ-factor competition assays, (ii) that previously defined mutations rendering the housekeeping σ70 less effective at competing with σ54 for limiting amounts of core RNA polymerase similarly suppress the requirement for DksA and ppGpp in vivo and (iii) that the extent to which ppGpp and DksA affect transcription from σ54 promoters in vivo reflects the innate affinity of the promoters for σ54-RNA polymerase holoenzyme in vitro. Based on these findings, we propose a passive model for ppGpp/DksA regulation of σ54-dependent transcription that depends on the potent negative effects of these regulatory molecules on transcription from powerful stringently regulated σ70 promoters. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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