Part of the ABC transporter complex LsrABCD involved in autoinducer 2 (AI-2) import. Probably responsible for the translocation of the substrate across the membrane (Probable). The complex is composed of two ATP-binding proteins (LsrA), two transmembrane proteins (LsrC and LsrD) and a solute-binding protein (LsrB). In the absence of AI-2, repressed by LsrR. Induced by AI-2, via release of the LsrR repressor. In the absence of glucose, induced by cAMP-CRP by direct binding to the upstream region of the lsr promoter. Belongs to the binding-protein-dependent transport system permease family. AraH/RbsC subfamily.