Three-dimensional structures of the ligand-binding domain of the bacterial aspartate receptor with and without a ligand

Abstract

The three-dimensional structure of an active, disulfide cross-linked dimer of the ligand-binding domain of the Salmonella typhimurium aspartate receptor and that of an aspartate complex have been determined by x-ray crystallographic methods at 2.4 and 2.0 angstrom resolution, respectively. A single subunit is a four-α-helix bundle with two long amino-terminal and carboxyl-terminal helices and two shorter helices that form a cylinder 20 Å in diameter and more than 70 Å long. The two subunits in the disulfide-bonded dimer are related by a crystallographic twofold axis in the apo structure, but by a noncrystallographic twofold axis in the aspartate complex structure. The latter structure reveals that the ligand binding site is located more than 60 Å from the presumed membrane surface and is at the interface of the two subunits. Aspartate binds between two α helices from one subunit and one α helix from the other in a highly charged pocket formed by three arginines. The comparison of the apo and aspartate complex structures shows only small structural changes in the individual subunits, except for one loop region that is disordered, but the subunits appear to change orientation relative to each other. The structures of the two forms of this protein provide a step toward understanding the mechanisms of transmembrane signaling.

Other Versions

No versions found

Links

PhilArchive



    Upload a copy of this work     Papers currently archived: 101,060

External links

Setup an account with your affiliations in order to access resources via your University's proxy server

Through your library

  • Only published works are available at libraries.

Similar books and articles

Analytics

Added to PP
2017-05-12

Downloads
9 (#1,521,134)

6 months
3 (#1,471,842)

Historical graph of downloads
How can I increase my downloads?

References found in this work

No references found.

Add more references