Nitrogen regulation of protein–protein interactions and transcript levels of GlnK PII regulator and AmtB ammonium transporter homologs in Archaea. Issue 5 (28th August 2013)

• Record Type: Journal Article
• Authors: Pedro‐Roig, Laia; Lange, Christian; Bonete, María José; Soppa, Jörg; Maupin‐Furlow, Julie
• Is Part Of: MicrobiologyOpen. Volume 2:Issue 5(2013:Oct.)
• Page Start: 826
• Page End: 840
• Publication Date: 2013-08-28
• Subjects: Microbiology -- Periodicals; 579
• DOI: 10.1002/mbo3.120
• Languages: English
• ISSNs: 2045-8827

Abstract

<abstract abstract-type="main" id="mbo3120-abs-0001"> <title>Abstract</title> <p>Gene homologs of GlnK PII regulators and AmtB‐type ammonium transporters are often paired on prokaryotic genomes, suggesting these proteins share an ancient functional relationship. Here, we demonstrate for the first time in Archaea that GlnK associates with AmtB in membrane fractions after ammonium shock, thus, providing a further insight into GlnK‐AmtB as an ancient nitrogen sensor pair. For this work, <italic>Haloferax mediterranei</italic> was advanced for study through the generation of a <italic>pyrE2</italic>‐based counterselection system that was used for targeted gene deletion and expression of Flag‐tagged proteins from their native promoters. AmtB1‐Flag was detected in membrane fractions of cells grown on nitrate and was found to coimmunoprecipitate with GlnK after ammonium shock. Thus, in analogy to bacteria, the archaeal GlnK PII may block the AmtB1 ammonium transporter under nitrogen‐rich conditions. In addition to this regulated protein–protein interaction, the archaeal <italic>amtB‐glnK</italic> gene pairs were found to be highly regulated by nitrogen availability with transcript levels high under conditions of nitrogen limitation and low during nitrogen excess. While transcript levels of <italic>glnK‐amtB</italic> are similarly regulated by nitrogen availability in bacteria, transcriptional regulators of the bacterial <italic>glnK</italic> promoter including activation by the two‐component signal transduction proteins NtrC (GlnG, NRI) and NtrB (GlnL, NRII) and sigma factor σ<sup>N</sup> (σ<sup>54</sup>) are not conserved in archaea suggesting a novel mechanism of transcriptional control.</p> </abstract>