1GCG

THE 1.9 ANGSTROMS X-RAY STRUCTURE OF A CLOSED UNLIGANDED FORM OF THE PERIPLASMIC GLUCOSE(SLASH)GALACTOSE RECEPTOR FROM SALMONELLA TYPHIMURIUM

Summary for 1GCG

• Entry DOI: 10.2210/pdb1gcg/pdb
• Descriptor: GALACTOSE/GLUCOSE-BINDING PROTEIN, CALCIUM ION (3 entities in total)
• Functional Keywords: galactose-binding protein
• Biological source: Salmonella typhimurium
• Cellular location: Periplasm: P23905
• Total number of polymer chains: 1
• Total formula weight: 33500.74

Authors

Flocco, M.M.,Mowbray, S.L. (deposition date: 1994-02-03, release date: 1994-05-31, Last modification date: 2024-02-07)

Primary citation

Flocco, M.M.,Mowbray, S.L.
The 1.9 A x-ray structure of a closed unliganded form of the periplasmic glucose/galactose receptor from Salmonella typhimurium.
J.Biol.Chem., 269:8931-8936, 1994

PubMed Abstract: The three-dimensional structure of a ligand-free closed form of the glucose/galactose binding protein from Salmonella typhimurium has been determined at a resolution of 1.9 A. The crystallographic R-factor for the refined structure is 17.9%. The model contains all the atoms of the 309 residues of the protein sequence, a calcium ion, and 174 water molecules. The root mean square (r.m.s.) deviations for the whole molecule are: 0.010 A for bond lengths and 2.44 degrees for bond angles, indicating a good stereochemistry for the model. This structure shows that the protein is able to close in the absence of ligand, adopting a conformation similar to the liganded form but slightly more open. Water molecules satisfy the hydrogen bonding ability of the hydrophilic side chains of the binding site in a manner which is reminiscent of the sugars' hydrogen-bonding patterns. Since packing forces are weak, the crystallization event is unlikely to trigger a change from an open to a closed conformation. Instead, the latter must be one of the species in equilibrium in solution which is selected by packing in the crystal lattice.

PubMed: 8132630

Experimental method

X-RAY DIFFRACTION (1.9 Å)