title: Hinge-bending motion of D-allose-binding protein from Escherichia coli: three open conformations.
abstract: Conformational changes of periplasmic binding proteins are essential for their function in chemotaxis and transport. The allose-binding protein from Escherichia coli is, like other receptors in its family, composed of two alpha/beta domains joined by a three-stranded hinge. In the previously determined structure of the closed, ligand-bound form (Chaudhuri, B. N., Ko, J., Park, C., Jones, T. A., and Mowbray, S. L. (1999) J. Mol. Biol. 286, 1519-1531), the ligand-binding site is buried between the two domains. We report here the structures of three distinct open, ligand-free forms of this receptor, one solved at 3.1-A resolution and two others at 1.7-A resolution. Together, these allow a description of the conformational changes associated with ligand binding. A few large, coupled torsional changes in the hinge strands are sufficient to generate the overall bending motion, with only minor disruption of the individual domains. Integral water molecules appear to act as structural "ball bearings" in this process. The conformational changes of the related ribose-binding protein follow a distinct pattern. The observed differences between the two proteins can be interpreted in the context of changes in sequence and in crystal packing and provide new insights into the nature of hinge bending motion in this class of periplasmic binding proteins.
authors.affiliation: Department of Cell and Molecular Biology, Uppsala University, BMC, Box 596, Uppsala SE 751 24, Sweden.
authors.forename: Ulrika
authors.initials: U
authors.lastname: Magnusson
authors.forename: Barnali Neel
authors.initials: BN
authors.lastname: Chaudhuri
authors.forename: Junsang
authors.initials: J
authors.lastname: Ko
authors.forename: Chankyu
authors.initials: C
authors.lastname: Park
authors.forename: T Alwyn
authors.initials: TA
authors.lastname: Jones
authors.forename: Sherry L
authors.initials: SL
authors.lastname: Mowbray
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004583:Electrons; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins; D008024:Ligands; D008958:Models, Molecular; D010100:Oxygen; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D017434:Protein Structure, Tertiary
chemical_list: D018528:ATP-Binding Cassette Transporters; C118436:D-allose binding protein, E coli; D029968:Escherichia coli Proteins; D008024:Ligands; D010100:Oxygen