PDBsum entry 2asr

Chemotaxis

PDB id: 2asr

Contents

Protein chain

142 a.a.

Ligands

SO4 ×2

Waters ×108

References listed in PDB file

Key reference

Title

The three-Dimensional structure of the aspartate receptor from escherichia coli.

Authors

J.U.Bowie, A.A.Pakula, M.I.Simon.

Ref.

Acta Crystallogr D Biol Crystallogr, 1995, 51, 145-154. [DOI no: 10.1107/S0907444994010498]

PubMed id

15299315

Abstract

The crystal structure of the periplasmic domain of the aspartate receptor from Escherichia coli has been solved and refined to an R-factor of 0.203 at 2.3 A, resolution. The dimeric protein is largely helical, with four helices from each monomer forming a four-helix bundle. The dimer interface is constructed from four helices, two from each subunit, also packed together in a four-helix bundle arrangement. A sulfate ion occupies the aspartate-binding site. All hydrogen bonds made to aspartate are substituted by direct or water-mediated hydrogen bonds to the sulfate. Comparison of the Escherichia coli aspartate-receptor structure with that of Salmonella typhimurium [Milburn, Prive, Milligan, Scott, Yeh, Jancarik, Koshland & Kim (1991). Science, 254, 1342-1347; Scott, Milligan, Milburn, Prive, Yeh, Koshland & Kim (1993). J. Mol. Biol. 232, 555-573] reveals strong conservation in the structure of the monomer, but more divergence in the orientation of the subunits with respect to one another. Mutations that render the Escherichia coli receptor incapable of responding to maltose are either located in spatially conserved sites or in regions of the structures that have high temperature factors and are therefore likely to be quite flexible. The inability of the receptor from Salmonella typhimurium to respond to maltose may, therefore, be because of differences in amino acids located on the binding surface rather than structural differences.

Figure 4.
Fig. 4. The AR-Ec dimer structure. (a) A ribbon drawing showing the sulfate bound in the aspartate-binding pocket in a ball-and-stick representation. (b) A stereoview of the Ca trace. The figure was produced using the program MOLSCRIPT (Kraulis, 1991).

Figure 7.
Fig. 7. Location of mal- mutations. The structure of AR-Ec (light grey) is shown superimposed on the structure of AR-St-apo (dark grey). Position of the mal- mutations are indicated on the AR-Ec structure by black balls at their Ca positions. The figure was produced using the program MOLSCRIPT (Kraulis, 1991)

The above figures are reprinted by permission from the IUCr: Acta Crystallogr D Biol Crystallogr (1995, 51, 145-154) copyright 1995.