The periplasmic-binding component of ABC transport systems specific for xylo-oligosaccharides; possesses type 2 periplasmic binding fold.
This group represents the periplasmic component of an ABC transport system XBP1 that shows preference for xylo-oligosaccharides in the order of xylotriose > xylobiose > xylotetraose. Members of this group belong to the type 2 periplasmic-binding fold superfamily. PBP2 proteins are comprised of two globular subdomains connected by a flexible hinge and bind their ligand in the cleft between these domains in a manner resembling a Venus flytrap. The majority of PBP2 proteins function in the uptake of small soluble substrates in eubacteria and archaea. After binding their specific ligand with high affinity, they can interact with a cognate membrane transport complex comprised of two integral membrane domains and two cytoplasmically located ATPase domains. This interaction triggers the ligand translocation across the cytoplasmic membrane energized by ATP hydrolysis.
Jiyao W et al.(2023). "The conserved domain database in 2023.",