Energy shifts induce membrane sequestration of DraG in Rhodospirillum rubrum independent of the ammonium transporters and diazotrophic conditions. Issue 16 (13th July 2018)

• Record Type: Journal Article
• Authors: Wang, Helen; Waluk, Dominik; Dixon, Ray; Nordlund, Stefan; Norén, Agneta
• Is Part Of: FEMS microbiology letters. Volume 365:Issue 16(2018:Aug.)
• Publication Date: 2018-07-13
• Subjects: metabolic regulation -- nitrogenase -- DraG -- energy switch-off; Microbiology -- Periodicals; 579
• DOI: 10.1093/femsle/fny176
• Languages: English
• ISSNs: 0378-1097

Abstract

ABSTRACT: Metabolic regulation of Rhodospirillum rubrum nitrogenase is mediated at the post-translational level by the enzymes DraT and DraG when subjected to changes in nitrogen or energy status. DraT is activated during switch-off, while DraG is inactivated by reversible membrane association. We confirm here that the ammonium transporter, AmtB1, rather than its paralog AmtB2, is required for ammonium induced switch-off. Amongst several substitutions at the N100 position in DraG, only N100K failed to locate to the membrane following ammonium shock, suggesting loss of interaction through charge repulsion. When switch-off was induced by lowering energy levels, either by darkness during photosynthetic growth or oxygen depletion under respiratory conditions, reversible membrane sequestration of DraG was independent of AmtB proteins and occurred even under non-diazotrophic conditions. We propose that under these conditions, changes in redox status or possibly membrane potential induce interactions between DraG and another membrane protein in response to the energy status. Abstract : DraG, an enzyme required for metabolic regulation of nitrogenase in Rhodospirillum rubrum, is regulated by reversible membrane sequestration during energy depletion, independent of diazotrophic conditions and presence of ammonium transporters.