1R9Q

structure analysis of ProX in complex with proline betaine

Summary for 1R9Q

• Entry DOI: 10.2210/pdb1r9q/pdb
• Related: 1R9L
• Descriptor: Glycine betaine-binding periplasmic protein, UNKNOWN ATOM OR ION, 1,1-DIMETHYL-PROLINIUM, ... (4 entities in total)
• Functional Keywords: periplasmic binding protein, cation-pi interactions, tryptophan box, protein binding
• Biological source: Escherichia coli
• Total number of polymer chains: 1
• Total formula weight: 33904.93

Authors

Schiefner, A.,Breed, J.,Bosser, L.,Kneip, S.,Gade, J.,Holtmann, G.,Diederichs, K.,Welte, W.,Bremer, E. (deposition date: 2003-10-30, release date: 2004-02-24, Last modification date: 2023-10-25)

Primary citation

Schiefner, A.,Breed, J.,Bosser, L.,Kneip, S.,Gade, J.,Holtmann, G.,Diederichs, K.,Welte, W.,Bremer, E.
Cation-pi Interactions as Determinants for Binding of the Compatible Solutes Glycine Betaine and Proline Betaine by the Periplasmic Ligand-binding Protein ProX from Escherichia coli
J.BIOL.CHEM., 279:5588-5596, 2004

PubMed Abstract: Compatible solutes such as glycine betaine and proline betaine are accumulated to exceedingly high intracellular levels by many organisms in response to high osmolarity to offset the loss of cell water. They are excluded from the immediate hydration shell of proteins and thereby stabilize their native structure. Despite their exclusion from protein surfaces, the periplasmic ligand-binding protein ProX from the Escherichia coli ATP-binding cassette transport system ProU binds the compatible solutes glycine betaine and proline betaine with high affinity and specificity. To understand the mechanism of compatible solute binding, we determined the high resolution structure of ProX in complex with its ligands glycine betaine and proline betaine. This crystallographic study revealed that cation-pi interactions between the positive charge of the quaternary amine of the ligands and three tryptophan residues forming a rectangular aromatic box are the key determinants of the high affinity binding of compatible solutes by ProX. The structural analysis was combined with site-directed mutagenesis of the ligand binding pocket to estimate the contributions of the tryptophan residues involved in binding.

PubMed: 14612446
DOI: 10.1074/jbc.M309771200

Experimental method

X-RAY DIFFRACTION (2.05 Å)