PDBsum entry 1sw5

Protein binding

PDB id: 1sw5

Contents

Protein chains

270 a.a. *

Metals

_MG

_CL ×8

Waters ×327

* Residue conservation analysis

PDB id:

1sw5

Name:

Protein binding

Title:

Crystal structure of prox from archeoglobus fulgidus in the ligand free form

Structure:

Osmoprotection protein (prox). Chain: a, b, c, d. Engineered: yes. Mutation: yes

Source:

Archaeoglobus fulgidus. Organism_taxid: 224325. Strain: dsm 4304. Gene: prox. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.80Å R-factor: 0.188 R-free: 0.214

Authors:

A.Schiefner,G.Holtmann,K.Diederichs,W.Welte,E.Bremer

Key ref:

A.Schiefner et al. (2004). Structural basis for the binding of compatible solutes by ProX from the hyperthermophilic archaeon Archaeoglobus fulgidus. J Biol Chem, 279, 48270-48281. PubMed id: 15308642 DOI: 10.1074/jbc.M403540200

Date:

30-Mar-04 Release date: 14-Sep-04

Protein chains

O29280  (O29280_ARCFU) -  Osmoprotection protein (ProX) from Archaeoglobus fulgidus (strain ATCC 49558 / DSM 4304 / JCM 9628 / NBRC 100126 / VC-16)

Seq: 292 a.a.

Struc: 270 a.a.

DOI no: 10.1074/jbc.M403540200

J Biol Chem 279:48270-48281 (2004)

PubMed id: 15308642

Structural basis for the binding of compatible solutes by ProX from the hyperthermophilic archaeon Archaeoglobus fulgidus.

A.Schiefner, G.Holtmann, K.Diederichs, W.Welte, E.Bremer.

ABSTRACT

Compatible solutes such as glycine betaine and proline betaine serve as protein stabilizers because of their preferential exclusion from protein surfaces. To use extracellular sources of this class of compounds as osmo-, cryo-, or thermoprotectants, Bacteria and Archaea have developed high affinity uptake systems of the ATP-binding cassette type. These transport systems require periplasmic- or extracellular-binding proteins that are able to bind the transported substance with high affinity. Therefore, binding proteins that bind compatible solutes have to avoid the exclusion of their ligands within the binding pocket. In the present study we addressed the question to how compatible solutes can be effectively bound by a protein at temperatures around 83 degrees C as this is done by the ligand-binding protein ProX from the hyperthermophilic archaeon Archaeoglobus fulgidus. We solved the structures of ProX without ligand and in complex with both of its natural ligands glycine betaine and proline betaine, as well as in complex with the artificial ligand trimethylammonium. Cation-pi interactions and non-classical hydrogen bonds between four tyrosine residues, a main chain carbonyl oxygen, and the ligand have been identified to be the key determinants in binding the quaternary amines of the three investigated ligands. The comparison of the ligand binding sites of ProX from A. fulgidus and the recently solved structure of ProX from Escherichia coli revealed a very similar solution for the problem of compatible solute binding, although both proteins share only a low degree of sequence identity. The residues involved in ligand binding are functionally equivalent but not conserved in the primary sequence.

Selected figure(s)

Figure 1.
FIG. 1. Overall structure of the open and closed conformation that ProX undergoes in a large conformational change from its unliganded open conformation (left) to the liganded closed form (right). In between (above the arrow) the three structures, ligands are shown that have been found to induce this conformational change, GB, PB, and TM, from left to right. Domain A (blue) is shown in the same orientation for both conformations, whereas the comparison shows that domain B (yellow) is relocated with respect to domain A. In the closed conformation the ligand GB is highlighted in red.

Figure 3.
FIG. 3. Superposition of the ProX binding site in the open and closed conformations. Stereo picture of the superposition of ProX in the open conformation (blue) onto the closed conformation (red). GB (green) is shown as the ligand in the closed form. Residues involved in ligand binding and the ligand are drawn as ball-and-stick model and labeled with their residue names.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2004, 279, 48270-48281) copyright 2004.

Figures were selected by an automated process.