Picture of industrial chimneys polluting horizon

Open Access research shaping international environmental governance...

Strathprints makes available scholarly Open Access content exploring environmental law and governance, in particular the work of the Strathclyde Centre for Environmental Law & Governance (SCELG) based within the School of Law.

SCELG aims to improve understanding of the trends, challenges and potential solutions across different interconnected areas of environmental law, including capacity-building for sustainable management of biodiversity, oceans, lands and freshwater, as well as for the fight against climate change. The intersection of international, regional, national and local levels of environmental governance, including the customary laws of indigenous peoples and local communities, and legal developments by private actors, is also a signifcant research specialism.

Explore Open Access research by SCELG or the School of Law. Or explore all of Strathclyde's Open Access research...

Nitric oxide-responsive interdomain regulation targets the σ54-interaction surface in the enhancer binding protein NorR

Bush, Matthew and Ghosh, Tamaswati and Tucker, Nicholas and Zhang, Xiaodong and Dixon, Ray (2010) Nitric oxide-responsive interdomain regulation targets the σ54-interaction surface in the enhancer binding protein NorR. Molecular Microbiology, 77 (5). pp. 1278-1288.

Full text not available in this repository. Request a copy from the Strathclyde author

Abstract

Bacterial enhancer binding proteins (bEBPs) are specialized transcriptional activators that assemble as hexameric rings in their active forms and utilize ATP hydrolysis to remodel the conformation of RNA polymerase containing the alternative sigma factor σ(54). Transcriptional activation by the NorR bEBP is controlled by a regulatory GAF domain that represses the ATPase activity of the central AAA+ domain in the absence of nitric oxide. Here, we investigate the mechanism of interdomain repression in NorR by characterizing substitutions in the AAA+ domain that bypass repression by the regulatory domain. Most of these substitutions are located in the vicinity of the surface-exposed loops that engage σ(54) during the ATP hydrolysis cycle or in the highly conserved GAFTGA motif that directly contacts σ(54). Biochemical studies suggest that the bypass mutations in the GAFTGA loop do not influence the DNA binding properties of NorR or the assembly of higher order oligomers in the presence of enhancer DNA, and as expected these variants retain the ability to activate open complex formation in vitro. We identify a crucial arginine residue in the GAF domain that is essential for interdomain repression and demonstrate that hydrophobic substitutions at this position suppress the bypass phenotype of the GAFTGA substitutions. These observations suggest a novel mechanism for negative regulation in bEBPs in which the GAF domain targets the σ(54)-interaction surface to prevent access of the AAA+ domain to the sigma factor.