3.A.1.1.53
Oligosaccharide transporter RafEFGK. RafE, the binding protein, has be extensively characterized.  It binds α-(1,6)-linked glucosides and galactosides of varying size, linkage, and monosaccharide composition with preference for the trisaccharides raffinose and panose. This preference is reflected in the α-(1,6)-galactoside uptake profile of the bacterium. Structures of RafE (BlG16BP) in complex with raffinose and panose revealed the basis for the ligand binding plasticity, which recognizes the non-reducing α-(1,6)-diglycosidic linkages in its ligands (Ejby et al. 2016). RafK has not be identified experimentally, but it may be NCIB protein acc# WP_022543180.1, ATP binding protein, annotated as UgpC, and this protein has been enterred into TCDB as RafK. Sugar binding substrates of RafE include: raffinose (highest affinity), panose, melibiose, stachyose, verbascose, isomaltose, isomaltotriose, isomaltotetraose, isomaltopentaose, isomaltohexaose, and isomaltoheptaose (Ejby et al. 2016).