Specificity and regulation of interaction between the PII and AmtB1 proteins in Rhodospirillum rubrum

David M. Wolfe, Yaoping Zhang, Gary P. Roberts*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


The nitrogen regulatory protein PII, 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 PII homolog, GlnJ, has higher affinity for an AmtB1-containing membrane than the other two PII 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-AmtB1 complex in the presence of ATP and 2-KG, supporting a role for PII as an energy sensor measuring the ratio of ATP to ADP. In the presence of saturating levels of ATP, the estimated Kd of 2-KG for GlnJ bound to AmtB1 is 340 μM, which is higher than that required for uridylylation of GlnJ in vitro, about 5 μM. This supports a model where multiple 2-KG and ATP molecules must bind a PII trimer to stimulate release of P II from AmtB1, in contrast to the lower 2-KG requirement for productive uridylylation of PII by GlnD.

Original languageEnglish
Pages (from-to)6861-6869
Number of pages9
JournalJournal of Bacteriology
Issue number19
StatePublished - Oct 2007
Externally publishedYes


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