RT Journal Article SR Electronic(1) A1 Teixeira, Pedro Filipe A1 Jonsson, Anders A1 Frank, Martina A1 Wang, He A1 Nordlund, StefanYR 2008 T1 Interaction of the signal transduction protein GlnJ with the cellular targets AmtB1, GlnE and GlnD in Rhodospirillum rubrum: dependence on manganese, 2-oxoglutarate and the ADP/ATP ratio JF Microbiology, VO 154 IS 8 SP 2336 OP 2347 DO https://doi.org/10.1099/mic.0.2008/017533-0 PB Microbiology Society, SN 1465-2080, AB The PII family of signal transduction proteins is widespread amongst the three domains of life, and its members have fundamental roles in the general control of nitrogen metabolism. These proteins exert their regulatory role by direct protein–protein interaction with a multitude of cellular targets. The interactions are dependent on the binding of metabolites such as ATP, ADP and 2-oxoglutarate (2-OG), and on whether or not the PII protein is modified. In the photosynthetic nitrogen-fixing bacterium Rhodospirillum rubrum three PII paralogues have been identified and termed GlnB, GlnJ and GlnK. In this report we analysed the interaction of GlnJ with known cellular targets such as the ammonium transporter AmtB1, the adenylyltransferase GlnE and the uridylyltransferase GlnD. Our results show that the interaction of GlnJ with cellular targets is regulated in vitro by the concentrations of manganese and 2-OG and the ADP : ATP ratio. Furthermore, we show here for the first time, to our knowledge, that in the interactions of GlnJ with the three different partners, the energy signal (ADP : ATP ratio) in fact overrides the carbon/nitrogen signal (2-OG). In addition, by generating specific amino acid substitutions in GlnJ we show that the interactions with different cellular targets are differentially affected, and the possible implications of these results are discussed. Our results are important to further the understanding of the regulatory role of PII proteins in R. rubrum, a photosynthetic bacterium in which the nitrogen fixation process and its intricate control mechanisms make the regulation of nitrogen metabolism even more complex than in other studied bacteria., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.2008/017533-0