title: Evidence for self-association of the alternative sigma factor σ54.
abstract: Sigma factor σ(54) has a distinct modus operandi for mediating the activation of bacterial RNA polymerase (RNAP) at promoter recognition motifs 12 and 24 bp upstream from transcription start sites. σ(54) was thought to act as monomer in all transcription steps. However, we provide evidence that σ(54) of Pseudomonas putida interacts stably with itself. The interface between monomers involves contacts in σ(54) regions I and III, sequences that play key roles in the transcription activation of σ(54)-RNAP holoenzyme. These roles include interactions with activator proteins and the -12 and -24 motifs. In particular, we detected inter-monomer contacts between region I, and between region I and the C-terminal portion of region III. Our results suggest a new auto-antagonistic regulatory state of σ(54).
authors: Department of Life Sciences, Università degli Studi di Milano, Milan, Italy.
authors: Massimo
authors: M
authors: Sabbatini
authors: Alessandro
authors: A
authors: Vezzoli
authors: Mario
authors: M
authors: Milani
authors: Giovanni
authors: G
authors: Bertoni
mesh_terms: D055503:Protein Multimerization; D016958:Pseudomonas putida / Q000378:metabolism*; D051877:RNA Polymerase Sigma 54 / Q000737:chemistry / Q000378:metabolism*; D012329:RNA, Bacterial / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D020798:Two-Hybrid System Techniques
chemical_list: D012329:RNA, Bacterial; D051877:RNA Polymerase Sigma 54