Part of an ABC transporter complex involved in low-affinity glycine betaine uptake. Probably responsible for the translocation of the substrate across the membrane. The complex is composed of two ATP-binding proteins (YehX), two transmembrane proteins (YehW and YehY) and a solute-binding protein (YehZ). Expression is sigma S-dependent. Induced by both osmotic shock and entry into stationary phase. Belongs to the binding-protein-dependent transport system permease family. CysTW subfamily. Was originally thought to be part of an osmoprotectant uptake system (PubMed:15251200). However, it was shown later that the complex does not mediate osmotic stress protection (PubMed:26325238).