Related Experiment Video
Updated: Mar 8, 2026

Glutamine Flux Imaging Using Genetically Encoded Sensors
Published on: July 31, 2014
Glutamine synthetase stabilizes the binding of GlnR to nitrogen fixation gene operators
Gabriela de C Fernandes1,2, Ksenia Hauf2, Fernando H Sant'Anna1
1Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Abstract:
Biological nitrogen fixation (BNF) is a high energy demanding process carried out by diazotrophic microorganisms that supply combined nitrogen to the biosphere. The genes related to BNF are strictly regulated, but these mechanisms are poorly understood in gram-positive bacteria. The transcription factor GlnR was proposed to regulate nitrogen fixation-related genes based on Paenibacillus comparative genomics. In order to validate this proposal, we investigated BNF regulatory sequences in Paenibacillus riograndensis SBR5T genome. We identified GlnR-binding sites flanking σA -binding sites upstream from BNF-related genes. GlnR binding to these sites was demonstrated by surface plasmon resonance spectroscopy. GlnR-DNA affinity is greatly enhanced when GlnR is in complex with feedback-inhibited (glutamine-occupied) glutamine synthetase (GS). GlnR-GS complex formation is also modulated by ATP and AMP. Thereby, gene repression exerted by the GlnR-GS complex is coupled with nitrogen (glutamine levels) and energetic status (ATP and AMP). Finally, we propose a DNA-looping model based on multiple operator sites that represents a strong and strict regulation for these genes.
More Related Videos
10:58Plant Promoter Analysis: Identification and Characterization of Root Nodule Specific Promoter in the Common Bean
Published on: December 23, 2017
06:45Monitoring Intraspecies Competition in a Bacterial Cell Population by Cocultivation of Fluorescently Labelled Strains
Published on: January 18, 2014
Related Concept Videos
Inorganic Nitrogen Assimilation
Stringent Response in E. coli
Activation and Inactivation of G Proteins
Prokaryotic Transcriptional Activators and Repressors
Transcription of prokaryotic...
Ligand Binding and Linkage
Regulation of Nuclear Protein Sorting