Galactose-binding site in Escherichia coli heat-labile enterotoxin (LT) and cholera toxin (CT) |
| |
Authors: | Ethan A. Merritt,Titia K. Sixma&dagger ,Kor H. Kalk,Ben A. M. van,Zanten Wim G. J. Hol |
| |
Affiliation: | Department of Biological Structure SM-20, University of Washington, Seattle, Washington 98195, USA.;BIOSON Research Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands. |
| |
Abstract: | The galactose-binding site in cholera toxin and the closely related heat-labile enterotoxin (LT) from Escherichia coli is an attractive target for the rational design of potential anti-cholera drugs, in this paper we analyse the molecular structure of this binding site as seen in several crystal structures, including that of an LT: galactose complex which we report here at 2.2 Å resolution. The binding surface on the free toxin contains several tightly associated water molecules and a relatively flexible loop consisting of residues 51–60 of the B subunit. During receptor binding this loop becomes tightly ordered by forming hydrogen bonds jointly to the GM1 pentasaccharide and to a set of water molecules which stabilize the toxin: receptor complex. |
| |
Keywords: | |
|
|