Substrate binding domain of ectoine/hydroxyectoine specific ABC transport system; the type 2 periplasmic binding protein fold.
This family represents the periplasmic substrate-binding component of ABC transport systems that involved in uptake of osmoprotectants (also termed compatible solutes) such as ectoine and hydroxyectoine. To counteract the efflux of water, bacteria and archaea accumulate the compatible solutes for a sustained adjustment to high osmolarity surroundings. This substrate-binding domain belongs to the type 2 periplasmic binding fold protein superfamily (PBP2). The PBP2 proteins are typically 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.
Jiyao W et al.(2023). "The conserved domain database in 2023.",