Communication between Esigma(54) , promoter DNA and the conserved threonine residue in the GAFTGA motif of the PspF sigma-dependent activator during transcription activation.
Conversion of Esigma(54) closed promoter complexes to open promoter complexes requires specialized activators which are members of the AAA (ATPases Associated with various cellular Activities) protein family. The ATP binding and hydrolysis activity of Esigma(54) activators is used in an energy coupling reaction to remodel the Esigma(54) closed promoter complex and to overcome the sigma(54)-imposed block on open complex formation. The remodelling target for the AAA activator within the Esigma(54) closed complex includes a complex interface contributed to by Region I of sigma(54), core RNA polymerase and a promoter DNA fork junction structure, comprising the Esigma(54) regulatory centre. One sigma(54) binding surface on Esigma(54) activators is a conserved sequence known as the GAFTGA motif. Here, we present a detailed characterization of the interaction between Region I of sigma(54) and the Escherichia coli AAA sigma(54) activator Phage shock protein F. Using Esigma(54) promoter complexes that mimic different conformations adopted by the DNA during open complex formation, we investigated the contribution of the conserved threonine residue in the GAFTGA motif to transcription activation. Our results suggest that the organization of the Esigma(54) regulatory centre, and in particular the conformation adopted by the sigma(54) Region I and the DNA fork junction structure during open complex formation, is communicated to the AAA activator via the conserved T residue of the GAFTGA motif.
Imperial College London, Department of Biological Sciences, Sir Alexander Fleming Building, South Kensington Campus, London, SW72AZ, UK.
Patricia
P
Bordes
Siva R
SR
Wigneshweraraj
Matthew
M
Chaney
Angel E
AE
Dago
Enrique
E
Morett
Martin
M
Buck
D000595:Amino Acid Sequence; D001483:Base Sequence; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D011487:Protein Conformation; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D013912:Threonine / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation
D029968:Escherichia coli Proteins; C098954:PspF protein, E coli; D012808:Sigma Factor; D015534:Trans-Activators; D013912:Threonine; D012321:DNA-Directed RNA Polymerases