Autoregulation of a bacterial σ factor explored by using segmental isotopic labeling and NMR

摘要

Bacterial σ factors combine with the catalytic core RNA polymerase to direct the process of transcription initiation through sequence- specific interactions with the 10 and 35 elements of promoter DNA. In the absence of core RNA polymerase, the DNA-binding function of σ is autoinhibited by its own N-terminal 90 amino acids (region 1.1), putatively by a direct interaction with conserved region 4.2, which binds the 35 promoter element. In the present work, this mechanism of autoinhibition was studied by using a combination of NMR spectroscopy and segmental isotopic labeling of a σ~70-like subunit from Thermotoga maritima. Our data argue strongly against a high-affinity interaction between these two domains.