Novel binding site identified in a hybrid between cholera toxin and heat-labile enterotoxin: 1.9 A crystal structure reveals the details.
Journal article, 2004
A hybrid between the B subunits of cholera toxin and Escherichia coli heat-labile enterotoxin has been described, which exhibits a novel binding specificity to blood group A and B type 2 determinants. In the present investigation, we have determined the crystal structure of this protein hybrid, termed LCTBK, in complex with the blood group A pentasaccharide GalNAcalpha3(Fucalpha2)Galbeta4(Fucalpha3)GlcNAcbeta, confirming not only the novel binding specificity but also a distinct new oligosaccharide binding site. Binding studies revealed that the new specificity can be ascribed to a single mutation (S4N) introduced into the sequence of Escherichia coli heat-labile enterotoxin. At a resolution of 1.9 A, the new binding site is resolved in excellent detail. Main features include a complex network of water molecules, which is well preserved by the parent toxins, and an unexpectedly modest contribution to binding by the critical residue Asn4, which interacts with the ligand only via a single water molecule.
Protein Structure
genetics
Molecular
genetics
Water
chemistry
Glycosphingolipids
chemistry
metabolism
chemistry
Humans
Drug Design
metabolism
Models
Tertiary
genetics
metabolism
Binding Sites
Asparagine
Recombinant Fusion Proteins
metabolism
chemistry
Bacterial Toxins
metabolism
chemistry
Crystallography
metabolism
genetics
chemistry
Molecular Sequence Data
Blood Group Antigens
Escherichia coli Proteins
genetics
metabolism
genetics
chemistry
Cholera Toxin
Molecular Structure
metabolism
Protein Binding
Enterotoxins
metabolism
chemistry
Oligosaccharides
Protein Subunits
X-Ray
metabolism
chemistry
Author
Åsa Holmner
Chalmers University of Technology
Michael Lebens
University of Gothenburg
Susann Teneberg
University of Gothenburg
Jonas Ångström
University of Gothenburg
M. Ökvist
University of Gothenburg
Ute Krengel
Chalmers, Department of Chemistry and Bioscience
Structure
0969-2126 (ISSN)
Vol. 12 9 1655-67Subject Categories (SSIF 2011)
MEDICAL AND HEALTH SCIENCES
DOI
10.1016/j.str.2004.06.022
PubMed
15341730