Periplasmic binding proteins specific to rhizopines
Periplasmic binding proteins specific to rhizopines, which are simple sugar-like compounds produced in the nodules induced by the symbiotic root nodule bacteria, such as Rhizobium and Sinorhizobium. Rhizopine-binding-like proteins from other bacteria are also included. Two inositol based rhizopine compounds are known to date: L-3-O-methly-scyllo-inosamine (3-O-MSI) and scyllo-inosamine. Bacterial strains that can metabolize rhizopine have a greater competitive advantage in nodulation and rhizopine synthesis is regulated by NifA/NtrA regulatory transcription activators which are maximally expressed at the onset of nitrogen fixation in bacteroids. The members of this group belong to the pentose/hexose sugar-binding protein family of the type I periplasmic binding protein superfamily.