Crystal Structures of the ATPase Subunit of the Glucose ABC Transporter from Sulfolobus solfataricus: Nucleotide-free and Nucleotide-bound Conformations

• Published in: Journal of molecular biology Vol. 330; no. 2; pp. 343 - 358
• Main Authors: Verdon, Grégory, Albers, Sonja V., Dijkstra, Bauke W., Driessen, Arnold J.M., Thunnissen, Andy-Mark W.H.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 04.07.2003
• Subjects: ABC-ATPase; Adenine Nucleotides - metabolism; Adenosine Triphosphatases - chemistry; Adenosine Triphosphatases - genetics; Adenosine Triphosphate - metabolism; Amino Acid Sequence; ATP-binding cassette; ATP-Binding Cassette Transporters - chemistry; ATP-Binding Cassette Transporters - genetics; Binding Sites; conformational changes; Crystallography, X-Ray; Magnesium - metabolism; Models, Molecular; Molecular Sequence Data; Protein Conformation; Protein Subunits; Q-loop; Sequence Homology, Amino Acid; Static Electricity; Sulfolobus - enzymology; Sulfolobus - genetics; X-ray crystallography; X-ray crystallography; ATP-binding cassette; ABC; conformational changes; ABC-ATPase; Q-loop
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1016/S0022-2836(03)00575-8

The ABC-ATPase GlcV energizes a binding protein-dependent ABC transporter that mediates glucose uptake in Sulfolobus solfataricus. Here, we report high-resolution crystal structures of GlcV in different states along its catalytic cycle: distinct monomeric nucleotide-free states and monomeric complexes with ADP-Mg2+ as a product-bound state, and with AMPPNP-Mg2+ as an ATP-like bound state. The structure of GlcV consists of a typical ABC-ATPase domain, comprising two subdomains, connected by a linker region to a C-terminal domain of unknown function. Comparisons of the nucleotide-free and nucleotide-bound structures of GlcV reveal re-orientations of the ABCα subdomain and the C-terminal domain relative to the ABCα/β subdomain, and switch-like rearrangements in the P-loop and Q-loop regions. Additionally, large conformational differences are observed between the GlcV structures and those of other ABC-ATPases, further emphasizing the inherent flexibility of these proteins. Notably, a comparison of the monomeric AMPPNP-Mg2+-bound GlcV structure with that of the dimeric ATP-Na+-bound LolD-E171Q mutant reveals a ±20° rigid body re-orientation of the ABCα subdomain relative to the ABCα/β subdomain, accompanied by a local conformational difference in the Q-loop. We propose that these differences represent conformational changes that may have a role in the mechanism of energy-transduction and/or allosteric control of the ABC-ATPase activity in bacterial importers.