Interaction of the membrane-bound GlnK-AmtB complex with the master regulator of nitrogen metabolism TnrA in Bacillus subtilis.
PII proteins are widespread and highly conserved signal transduction proteins occurring in bacteria, Archaea, and plants and play pivotal roles in controlling nitrogen assimilatory metabolism. This study reports on biochemical properties of the PII-homologue GlnK (originally termed NrgB) in Bacillus subtilis (BsGlnK). Like other PII proteins, the native BsGlnK protein has a trimeric structure and readily binds ATP in the absence of divalent cations, whereas 2-oxoglutarate is only weakly bound. In contrast to other PII-like proteins, Mg2+ severely affects its ATP-binding properties. BsGlnK forms a tight complex with the membrane-bound ammonium transporter AmtB (NrgA), from which it can be relieved by millimolar concentrations of ATP. Immunoprecipitation and co-localization experiments identified a novel interaction between the BsGlnK-AmtB complex and the major transcription factor of nitrogen metabolism, TnrA. In vitro in the absence of ATP, TnrA is completely tethered to membrane (AmtB)-bound GlnK, whereas in extracts from BsGlnK- or AmtB-deficient cells, TnrA is entirely soluble. The presence of 4 mm ATP leads to concomitant solubilization of BsGlnK and TnrA. This ATP-dependent membrane re-localization of TnrA by BsGlnK/AmtB may present a novel mechanism to control the global nitrogen-responsive transcription regulator TnrA in B. subtilis under certain physiological conditions.
Heinrich
Annette
A
Institut für Mikrobiologie und Molekularbiologie, Justus-Liebig-Universität Giessen, Heinrich-Buff-Ring 26-32, D-35392 Giessen, Germany.
Woyda
Kathrin
K
Brauburger
Katja
K
Meiss
Gregor
G
Detsch
Christian
C
Stülke
Jörg
J
Forchhammer
Karl
K
D001412:Bacillus subtilis / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D051922:PII Nitrogen Regulatory Proteins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*
D001426:Bacterial Proteins; D008565:Membrane Proteins; C085245:NrgA protein, Bacillus subtilis; C085246:NrgB protein, Bacillus subtilis; D051922:PII Nitrogen Regulatory Proteins; D012097:Repressor Proteins; C101458:ScgR protein, Bacillus subtilis; D014157:Transcription Factors; D009584:Nitrogen