Snapshots of the maltose transporter during ATP hydrolysis.

ATP-binding cassette transporters are powered by ATP, but the mechanism by which these transporters hydrolyze ATP is unclear. In this study, four crystal structures of the full-length wild-type maltose transporter, stabilized by adenosine 5'-(β,γ-imido)triphosphate or ADP in conjunction with phosphate analogs BeF(3)(-), VO(4)(3-), or AIF(4)(-), were determined to 2.2- to 2.4-Å resolution. These structures led to the assignment of two enzymatic states during ATP hydrolysis and demonstrate specific functional roles of highly conserved residues in the nucleotide-binding domain, suggesting that ATP-binding cassette transporters catalyze ATP hydrolysis via a general base mechanism.