The bacteriophage T4 transcriptional activator MotA accepts various base-pair changes within its binding sequence.

@article{Marshall1999TheBT,
  title={The bacteriophage T4 transcriptional activator MotA accepts various base-pair changes within its binding sequence.},
  author={P Marshall and M. Sharma and Deborah M. Hinton},
  journal={Journal of molecular biology},
  year={1999},
  volume={285 3},
  pages={
          931-44
        }
}
During infection, bacteriophage T4 regulates three sets of genes: early, middle, and late. The host RNA polymerase is capable of transcribing early genes, but middle transcription requires the T4-encoded transcriptional activator, MotA protein, and the T4 co-activator, AsiA protein, both of which bind to the sigma 70 (sigma70) subunit of RNA polymerase. MotA also binds a DNA sequence (a MotA box), centered at position -30. The identification of more than 20 middle promoters suggested that a… 
Binding of the bacteriophage T4 transcriptional activator, MotA, to T4 middle promoter DNA: evidence for both major and minor groove contacts.
TLDR
Investigation of how the loss or modification of base determinants within the MotA box sequence 5'TTTGCTTTA3' (positions -34 to -26 of a middle promoter) affects MotA function suggests that the N-terminal region of MotA is needed for an interaction between MotA and sigma(70).
Transcriptional takeover by sigma appropriation: remodelling of the sigma70 subunit of Escherichia coli RNA polymerase by the bacteriophage T4 activator MotA and co-activator AsiA.
TLDR
This review discusses how these interactions accomplish the switch to T4 middle promoters by inhibiting the typical contacts of the C-terminal region of sigma(70), region 4, with the host -35 DNA element and with other subunits of polymerase.
The Bacteriophage T 4 Transcription Activator MotA Interacts with the FarC-Terminal Region of the 70 Subunit of Escherichia coli RNA Polymerase
TLDR
The results support a model for MotA-dependent activation in which protein-protein contact between DNA-bound MotA and the far-C-terminal region of 70 helps to substitute functionally for an interaction between 70 and a promoter 35 element.
The Bacteriophage T4 Transcription Activator MotA Interacts with the Far-C-Terminal Region of the σ70 Subunit of Escherichia coli RNA Polymerase
TLDR
The results support a model for MotA-dependent activation in which protein-protein contact between DNA-bound MotA and the far-C-terminal region of sigma70 helps to substitute functionally for an interaction between s Sigma70 and a promoter -35 element.
A Mutation within the β Subunit of Escherichia coli RNA Polymerase Impairs Transcription from Bacteriophage T4 Middle Promoters
TLDR
The results suggest that the presence of MotA and AsiA may impair the function of this loop or that this portion of the β subunit may influence interactions among MotA, Asi a, and RNA polymerase.
The phage T4 MotA transcription factor contains a novel DNA binding motif that specifically recognizes modified DNA
TLDR
This work reveals how a DNA modification can extend the uniqueness of small DNA motifs to facilitate the specificity of protein-DNA interactions.
Sigma competition: the contest between bacteriophage T4 middle and late transcription.
TLDR
In bacterial transcription, diverse sigma-family promoter recognition proteins compete for a common RNA polymerase core, and the largest contribution to the middle-late competition is made by gp55, the late sigma factor, but not enough of gp55 is produced during T4 infection to shut off middle transcription by direct competition with sigma(70).
Transcriptional control in the prereplicative phase of T4 development
TLDR
T4 sigma appropriation reveals how a specific domain within RNA polymerase can be remolded and then exploited to alter promoter specificity.
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TLDR
The isolation and characterization of a protein designated Mot21, in which the first 8 codons of the wild-type motA sequence have been replaced with 11 different codons are reported, suggesting that this interaction is necessary for transcriptional activation and that the Mot21 defect arises because Mot21 cannot form this contact like theWild-type activator.
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TLDR
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TLDR
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TLDR
In vitro, purified MotA and AsiA proteins are both necessary and sufficient to activate transcription initiation at T4 middle promoters by the E. coli RNA polymerase in a sigma 70-dependent manner.
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TLDR
It is concluded that AsiA inhibits transcription from Escherichia coli and T4 early promoters by counteracting the recognition of region 4.2 of σ70 with the −35 hexamer.
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TLDR
It is proposed that AsiA modulates initial DNA binding by the RNA polymerase, switching promoter usage at the level of closed complex formation.
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