Part of the ABC transporter complex GbuABC involved in glycine betaine uptake. Responsible for energy coupling to the transport system. Involved, with BetL and OpuC, in osmoprotection and cryoprotection of Listeria. Can also uptake carnitine when carnitine is abundant in the growth medium. ATP + H2O + quaternary ammonium(out) = ADP + H(+) + phosphate + quaternary ammonium(in) The complex is activated by an osmotic gradient or by low temperature. The complex is composed of two ATP-binding proteins (GbuA), two transmembrane proteins (GbuB) and a solute-binding protein (GbuC). Mutants are impaired in the transport of glycine betaine at elevated osmolarity and at decreased temperature. Belongs to the ABC transporter superfamily.