title: Specificity and regulation of interaction between the PII and AmtB1 proteins in Rhodospirillum rubrum.
abstract: The nitrogen regulatory protein P(II) and the ammonia gas channel AmtB are both found in most prokaryotes. Interaction between these two proteins has been observed in several organisms and may regulate the activities of both proteins. The regulation of their interaction is only partially understood, and we show that in Rhodospirillum rubrum one P(II) homolog, GlnJ, has higher affinity for an AmtB(1)-containing membrane than the other two P(II) homologs, GlnB and GlnK. This interaction strongly favors the nonuridylylated form of GlnJ and is disrupted by high levels of 2-ketoglutarate (2-KG) in the absence of ATP or low levels of 2-KG in the presence of ATP. ADP inhibits the destabilization of the GlnJ-AmtB(1) complex in the presence of ATP and 2-KG, supporting a role for P(II) as an energy sensor measuring the ratio of ATP to ADP. In the presence of saturating levels of ATP, the estimated K(d) of 2-KG for GlnJ bound to AmtB(1) is 340 microM, which is higher than that required for uridylylation of GlnJ in vitro, about 5 microM. This supports a model where multiple 2-KG and ATP molecules must bind a P(II) trimer to stimulate release of P(II) from AmtB(1), in contrast to the lower 2-KG requirement for productive uridylylation of P(II) by GlnD.
authors.affiliation: Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Wolfe
authors.forename: Yaoping
authors.initials: Y
authors.lastname: Zhang
authors.forename: Gary P
authors.initials: GP
authors.lastname: Roberts
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D007656:Ketoglutaric Acids / Q000494:pharmacology; D051922:PII Nitrogen Regulatory Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012247:Rhodospirillum rubrum / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D027682:Cation Transport Proteins; D007656:Ketoglutaric Acids; D051922:PII Nitrogen Regulatory Proteins; D000644:Quaternary Ammonium Compounds; C404143:PIID regulatory protein, Bacteria; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate